diff --git a/bundlepolicy.go b/bundlepolicy.go
index ea6dad5aeb0..7e3d6c506fa 100644
--- a/bundlepolicy.go
+++ b/bundlepolicy.go
@@ -14,11 +14,14 @@ import (
 type BundlePolicy int
 
 const (
+	// BundlePolicyUnknown is the enum's zero-value
+	BundlePolicyUnknown BundlePolicy = iota
+
 	// BundlePolicyBalanced indicates to gather ICE candidates for each
 	// media type in use (audio, video, and data). If the remote endpoint is
 	// not bundle-aware, negotiate only one audio and video track on separate
 	// transports.
-	BundlePolicyBalanced BundlePolicy = iota + 1
+	BundlePolicyBalanced
 
 	// BundlePolicyMaxCompat indicates to gather ICE candidates for each
 	// track. If the remote endpoint is not bundle-aware, negotiate all media
@@ -47,7 +50,7 @@ func newBundlePolicy(raw string) BundlePolicy {
 	case bundlePolicyMaxBundleStr:
 		return BundlePolicyMaxBundle
 	default:
-		return BundlePolicy(Unknown)
+		return BundlePolicyUnknown
 	}
 }
 
diff --git a/bundlepolicy_test.go b/bundlepolicy_test.go
index 747fb901d71..2fc3c2e6bdc 100644
--- a/bundlepolicy_test.go
+++ b/bundlepolicy_test.go
@@ -14,7 +14,7 @@ func TestNewBundlePolicy(t *testing.T) {
 		policyString   string
 		expectedPolicy BundlePolicy
 	}{
-		{unknownStr, BundlePolicy(Unknown)},
+		{ErrUnknownType.Error(), BundlePolicyUnknown},
 		{"balanced", BundlePolicyBalanced},
 		{"max-compat", BundlePolicyMaxCompat},
 		{"max-bundle", BundlePolicyMaxBundle},
@@ -34,7 +34,7 @@ func TestBundlePolicy_String(t *testing.T) {
 		policy         BundlePolicy
 		expectedString string
 	}{
-		{BundlePolicy(Unknown), unknownStr},
+		{BundlePolicyUnknown, ErrUnknownType.Error()},
 		{BundlePolicyBalanced, "balanced"},
 		{BundlePolicyMaxCompat, "max-compat"},
 		{BundlePolicyMaxBundle, "max-bundle"},
diff --git a/constants.go b/constants.go
index 94ba78494a6..70778506b59 100644
--- a/constants.go
+++ b/constants.go
@@ -6,11 +6,6 @@ package webrtc
 import "github.com/pion/dtls/v2"
 
 const (
-	// Unknown defines default public constant to use for "enum" like struct
-	// comparisons when no value was defined.
-	Unknown    = iota
-	unknownStr = "unknown"
-
 	// Equal to UDP MTU
 	receiveMTU = 1460
 
diff --git a/datachannelstate.go b/datachannelstate.go
index 55dc916e972..848d94ca89d 100644
--- a/datachannelstate.go
+++ b/datachannelstate.go
@@ -7,10 +7,13 @@ package webrtc
 type DataChannelState int
 
 const (
+	// DataChannelStateUnknown is the enum's zero-value
+	DataChannelStateUnknown DataChannelState = iota
+
 	// DataChannelStateConnecting indicates that the data channel is being
 	// established. This is the initial state of DataChannel, whether created
 	// with CreateDataChannel, or dispatched as a part of an DataChannelEvent.
-	DataChannelStateConnecting DataChannelState = iota + 1
+	DataChannelStateConnecting
 
 	// DataChannelStateOpen indicates that the underlying data transport is
 	// established and communication is possible.
@@ -44,7 +47,7 @@ func newDataChannelState(raw string) DataChannelState {
 	case dataChannelStateClosedStr:
 		return DataChannelStateClosed
 	default:
-		return DataChannelState(Unknown)
+		return DataChannelStateUnknown
 	}
 }
 
diff --git a/datachannelstate_test.go b/datachannelstate_test.go
index cb658a64e13..64426089523 100644
--- a/datachannelstate_test.go
+++ b/datachannelstate_test.go
@@ -14,7 +14,7 @@ func TestNewDataChannelState(t *testing.T) {
 		stateString   string
 		expectedState DataChannelState
 	}{
-		{unknownStr, DataChannelState(Unknown)},
+		{ErrUnknownType.Error(), DataChannelStateUnknown},
 		{"connecting", DataChannelStateConnecting},
 		{"open", DataChannelStateOpen},
 		{"closing", DataChannelStateClosing},
@@ -35,7 +35,7 @@ func TestDataChannelState_String(t *testing.T) {
 		state          DataChannelState
 		expectedString string
 	}{
-		{DataChannelState(Unknown), unknownStr},
+		{DataChannelStateUnknown, ErrUnknownType.Error()},
 		{DataChannelStateConnecting, "connecting"},
 		{DataChannelStateOpen, "open"},
 		{DataChannelStateClosing, "closing"},
diff --git a/dtlsrole.go b/dtlsrole.go
index 9cee581d9ec..40a14e87214 100644
--- a/dtlsrole.go
+++ b/dtlsrole.go
@@ -11,10 +11,13 @@ import (
 type DTLSRole byte
 
 const (
+	// DTLSRoleUnknown is the enum's zero-value
+	DTLSRoleUnknown DTLSRole = iota
+
 	// DTLSRoleAuto defines the DTLS role is determined based on
 	// the resolved ICE role: the ICE controlled role acts as the DTLS
 	// client and the ICE controlling role acts as the DTLS server.
-	DTLSRoleAuto DTLSRole = iota + 1
+	DTLSRoleAuto
 
 	// DTLSRoleClient defines the DTLS client role.
 	DTLSRoleClient
@@ -51,7 +54,7 @@ func (r DTLSRole) String() string {
 	case DTLSRoleServer:
 		return "server"
 	default:
-		return unknownStr
+		return ErrUnknownType.Error()
 	}
 }
 
diff --git a/dtlsrole_test.go b/dtlsrole_test.go
index 0c9a5692627..c709f31dfeb 100644
--- a/dtlsrole_test.go
+++ b/dtlsrole_test.go
@@ -16,7 +16,7 @@ func TestDTLSRole_String(t *testing.T) {
 		role           DTLSRole
 		expectedString string
 	}{
-		{DTLSRole(Unknown), unknownStr},
+		{DTLSRoleUnknown, ErrUnknownType.Error()},
 		{DTLSRoleAuto, "auto"},
 		{DTLSRoleClient, "client"},
 		{DTLSRoleServer, "server"},
diff --git a/dtlstransportstate.go b/dtlstransportstate.go
index 573dd4bf038..c938ae2c0f5 100644
--- a/dtlstransportstate.go
+++ b/dtlstransportstate.go
@@ -7,9 +7,12 @@ package webrtc
 type DTLSTransportState int
 
 const (
+	// DTLSTransportStateUnknown is the enum's zero-value
+	DTLSTransportStateUnknown DTLSTransportState = iota
+
 	// DTLSTransportStateNew indicates that DTLS has not started negotiating
 	// yet.
-	DTLSTransportStateNew DTLSTransportState = iota + 1
+	DTLSTransportStateNew
 
 	// DTLSTransportStateConnecting indicates that DTLS is in the process of
 	// negotiating a secure connection and verifying the remote fingerprint.
@@ -52,7 +55,7 @@ func newDTLSTransportState(raw string) DTLSTransportState {
 	case dtlsTransportStateFailedStr:
 		return DTLSTransportStateFailed
 	default:
-		return DTLSTransportState(Unknown)
+		return DTLSTransportStateUnknown
 	}
 }
 
diff --git a/dtlstransportstate_test.go b/dtlstransportstate_test.go
index f5e61a410a5..06ec0dfa3bd 100644
--- a/dtlstransportstate_test.go
+++ b/dtlstransportstate_test.go
@@ -14,7 +14,7 @@ func TestNewDTLSTransportState(t *testing.T) {
 		stateString   string
 		expectedState DTLSTransportState
 	}{
-		{unknownStr, DTLSTransportState(Unknown)},
+		{ErrUnknownType.Error(), DTLSTransportStateUnknown},
 		{"new", DTLSTransportStateNew},
 		{"connecting", DTLSTransportStateConnecting},
 		{"connected", DTLSTransportStateConnected},
@@ -36,7 +36,7 @@ func TestDTLSTransportState_String(t *testing.T) {
 		state          DTLSTransportState
 		expectedString string
 	}{
-		{DTLSTransportState(Unknown), unknownStr},
+		{DTLSTransportStateUnknown, ErrUnknownType.Error()},
 		{DTLSTransportStateNew, "new"},
 		{DTLSTransportStateConnecting, "connecting"},
 		{DTLSTransportStateConnected, "connected"},
diff --git a/icecandidatetype.go b/icecandidatetype.go
index 01f35119600..e77098d581a 100644
--- a/icecandidatetype.go
+++ b/icecandidatetype.go
@@ -13,12 +13,15 @@ import (
 type ICECandidateType int
 
 const (
+	// ICECandidateTypeUnknown is the enum's zero-value
+	ICECandidateTypeUnknown ICECandidateType = iota
+
 	// ICECandidateTypeHost indicates that the candidate is of Host type as
 	// described in https://tools.ietf.org/html/rfc8445#section-5.1.1.1. A
 	// candidate obtained by binding to a specific port from an IP address on
 	// the host. This includes IP addresses on physical interfaces and logical
 	// ones, such as ones obtained through VPNs.
-	ICECandidateTypeHost ICECandidateType = iota + 1
+	ICECandidateTypeHost
 
 	// ICECandidateTypeSrflx indicates the the candidate is of Server
 	// Reflexive type as described
@@ -60,7 +63,7 @@ func NewICECandidateType(raw string) (ICECandidateType, error) {
 	case iceCandidateTypeRelayStr:
 		return ICECandidateTypeRelay, nil
 	default:
-		return ICECandidateType(Unknown), fmt.Errorf("%w: %s", errICECandidateTypeUnknown, raw)
+		return ICECandidateTypeUnknown, fmt.Errorf("%w: %s", errICECandidateTypeUnknown, raw)
 	}
 }
 
@@ -92,7 +95,7 @@ func getCandidateType(candidateType ice.CandidateType) (ICECandidateType, error)
 	default:
 		// NOTE: this should never happen[tm]
 		err := fmt.Errorf("%w: %s", errICEInvalidConvertCandidateType, candidateType.String())
-		return ICECandidateType(Unknown), err
+		return ICECandidateTypeUnknown, err
 	}
 }
 
diff --git a/icecandidatetype_test.go b/icecandidatetype_test.go
index 993a0be9edd..10969b12fde 100644
--- a/icecandidatetype_test.go
+++ b/icecandidatetype_test.go
@@ -15,7 +15,7 @@ func TestICECandidateType(t *testing.T) {
 		shouldFail   bool
 		expectedType ICECandidateType
 	}{
-		{unknownStr, true, ICECandidateType(Unknown)},
+		{ErrUnknownType.Error(), true, ICECandidateTypeUnknown},
 		{"host", false, ICECandidateTypeHost},
 		{"srflx", false, ICECandidateTypeSrflx},
 		{"prflx", false, ICECandidateTypePrflx},
@@ -40,7 +40,7 @@ func TestICECandidateType_String(t *testing.T) {
 		cType          ICECandidateType
 		expectedString string
 	}{
-		{ICECandidateType(Unknown), unknownStr},
+		{ICECandidateTypeUnknown, ErrUnknownType.Error()},
 		{ICECandidateTypeHost, "host"},
 		{ICECandidateTypeSrflx, "srflx"},
 		{ICECandidateTypePrflx, "prflx"},
diff --git a/icecomponent.go b/icecomponent.go
index c65a893dcd8..ae8f230fbf5 100644
--- a/icecomponent.go
+++ b/icecomponent.go
@@ -8,12 +8,15 @@ package webrtc
 type ICEComponent int
 
 const (
+	// ICEComponentUnknown is the enum's zero-value
+	ICEComponentUnknown ICEComponent = iota
+
 	// ICEComponentRTP indicates that the ICE Transport is used for RTP (or
 	// RTCP multiplexing), as defined in
 	// https://tools.ietf.org/html/rfc5245#section-4.1.1.1. Protocols
 	// multiplexed with RTP (e.g. data channel) share its component ID. This
 	// represents the component-id value 1 when encoded in candidate-attribute.
-	ICEComponentRTP ICEComponent = iota + 1
+	ICEComponentRTP
 
 	// ICEComponentRTCP indicates that the ICE Transport is used for RTCP as
 	// defined by https://tools.ietf.org/html/rfc5245#section-4.1.1.1. This
@@ -34,7 +37,7 @@ func newICEComponent(raw string) ICEComponent {
 	case iceComponentRTCPStr:
 		return ICEComponentRTCP
 	default:
-		return ICEComponent(Unknown)
+		return ICEComponentUnknown
 	}
 }
 
diff --git a/icecomponent_test.go b/icecomponent_test.go
index 6d71f0a4ced..9d2bb3635b1 100644
--- a/icecomponent_test.go
+++ b/icecomponent_test.go
@@ -14,7 +14,7 @@ func TestICEComponent(t *testing.T) {
 		componentString   string
 		expectedComponent ICEComponent
 	}{
-		{unknownStr, ICEComponent(Unknown)},
+		{ErrUnknownType.Error(), ICEComponentUnknown},
 		{"rtp", ICEComponentRTP},
 		{"rtcp", ICEComponentRTCP},
 	}
@@ -33,7 +33,7 @@ func TestICEComponent_String(t *testing.T) {
 		state          ICEComponent
 		expectedString string
 	}{
-		{ICEComponent(Unknown), unknownStr},
+		{ICEComponentUnknown, ErrUnknownType.Error()},
 		{ICEComponentRTP, "rtp"},
 		{ICEComponentRTCP, "rtcp"},
 	}
diff --git a/iceconnectionstate.go b/iceconnectionstate.go
index e52e1328aed..4b7deb802fe 100644
--- a/iceconnectionstate.go
+++ b/iceconnectionstate.go
@@ -7,11 +7,14 @@ package webrtc
 type ICEConnectionState int
 
 const (
+	// ICEConnectionStateUnknown is the enum's zero-value
+	ICEConnectionStateUnknown ICEConnectionState = iota
+
 	// ICEConnectionStateNew indicates that any of the ICETransports are
 	// in the "new" state and none of them are in the "checking", "disconnected"
 	// or "failed" state, or all ICETransports are in the "closed" state, or
 	// there are no transports.
-	ICEConnectionStateNew ICEConnectionState = iota + 1
+	ICEConnectionStateNew
 
 	// ICEConnectionStateChecking indicates that any of the ICETransports
 	// are in the "checking" state and none of them are in the "disconnected"
@@ -71,7 +74,7 @@ func NewICEConnectionState(raw string) ICEConnectionState {
 	case iceConnectionStateClosedStr:
 		return ICEConnectionStateClosed
 	default:
-		return ICEConnectionState(Unknown)
+		return ICEConnectionStateUnknown
 	}
 }
 
diff --git a/iceconnectionstate_test.go b/iceconnectionstate_test.go
index 595e66abd7a..5f4259bd295 100644
--- a/iceconnectionstate_test.go
+++ b/iceconnectionstate_test.go
@@ -14,7 +14,7 @@ func TestNewICEConnectionState(t *testing.T) {
 		stateString   string
 		expectedState ICEConnectionState
 	}{
-		{unknownStr, ICEConnectionState(Unknown)},
+		{ErrUnknownType.Error(), ICEConnectionStateUnknown},
 		{"new", ICEConnectionStateNew},
 		{"checking", ICEConnectionStateChecking},
 		{"connected", ICEConnectionStateConnected},
@@ -38,7 +38,7 @@ func TestICEConnectionState_String(t *testing.T) {
 		state          ICEConnectionState
 		expectedString string
 	}{
-		{ICEConnectionState(Unknown), unknownStr},
+		{ICEConnectionStateUnknown, ErrUnknownType.Error()},
 		{ICEConnectionStateNew, "new"},
 		{ICEConnectionStateChecking, "checking"},
 		{ICEConnectionStateConnected, "connected"},
diff --git a/icegathererstate.go b/icegathererstate.go
index b90acd33eed..b78df5fc5f6 100644
--- a/icegathererstate.go
+++ b/icegathererstate.go
@@ -11,9 +11,12 @@ import (
 type ICEGathererState uint32
 
 const (
+	// ICEGathererStateUnknown is the enum's zero-value
+	ICEGathererStateUnknown ICEGathererState = iota
+
 	// ICEGathererStateNew indicates object has been created but
 	// gather() has not been called.
-	ICEGathererStateNew ICEGathererState = iota + 1
+	ICEGathererStateNew
 
 	// ICEGathererStateGathering indicates gather() has been called,
 	// and the ICEGatherer is in the process of gathering candidates.
@@ -38,7 +41,7 @@ func (s ICEGathererState) String() string {
 	case ICEGathererStateClosed:
 		return "closed"
 	default:
-		return unknownStr
+		return ErrUnknownType.Error()
 	}
 }
 
diff --git a/icegathererstate_test.go b/icegathererstate_test.go
index 71c4fe35aeb..a618cc816c5 100644
--- a/icegathererstate_test.go
+++ b/icegathererstate_test.go
@@ -14,7 +14,7 @@ func TestICEGathererState_String(t *testing.T) {
 		state          ICEGathererState
 		expectedString string
 	}{
-		{ICEGathererState(Unknown), unknownStr},
+		{ICEGathererStateUnknown, ErrUnknownType.Error()},
 		{ICEGathererStateNew, "new"},
 		{ICEGathererStateGathering, "gathering"},
 		{ICEGathererStateComplete, "complete"},
diff --git a/icegatheringstate.go b/icegatheringstate.go
index 1925dddbfe0..13ea2f73d4e 100644
--- a/icegatheringstate.go
+++ b/icegatheringstate.go
@@ -7,10 +7,13 @@ package webrtc
 type ICEGatheringState int
 
 const (
+	// ICEGatheringStateUnknown is the enum's zero-value
+	ICEGatheringStateUnknown ICEGatheringState = iota
+
 	// ICEGatheringStateNew indicates that any of the ICETransports are
 	// in the "new" gathering state and none of the transports are in the
 	// "gathering" state, or there are no transports.
-	ICEGatheringStateNew ICEGatheringState = iota + 1
+	ICEGatheringStateNew
 
 	// ICEGatheringStateGathering indicates that any of the ICETransports
 	// are in the "gathering" state.
@@ -38,7 +41,7 @@ func NewICEGatheringState(raw string) ICEGatheringState {
 	case iceGatheringStateCompleteStr:
 		return ICEGatheringStateComplete
 	default:
-		return ICEGatheringState(Unknown)
+		return ICEGatheringStateUnknown
 	}
 }
 
diff --git a/icegatheringstate_test.go b/icegatheringstate_test.go
index 018688cc35e..6220a54385c 100644
--- a/icegatheringstate_test.go
+++ b/icegatheringstate_test.go
@@ -14,7 +14,7 @@ func TestNewICEGatheringState(t *testing.T) {
 		stateString   string
 		expectedState ICEGatheringState
 	}{
-		{unknownStr, ICEGatheringState(Unknown)},
+		{ErrUnknownType.Error(), ICEGatheringStateUnknown},
 		{"new", ICEGatheringStateNew},
 		{"gathering", ICEGatheringStateGathering},
 		{"complete", ICEGatheringStateComplete},
@@ -34,7 +34,7 @@ func TestICEGatheringState_String(t *testing.T) {
 		state          ICEGatheringState
 		expectedString string
 	}{
-		{ICEGatheringState(Unknown), unknownStr},
+		{ICEGatheringStateUnknown, ErrUnknownType.Error()},
 		{ICEGatheringStateNew, "new"},
 		{ICEGatheringStateGathering, "gathering"},
 		{ICEGatheringStateComplete, "complete"},
diff --git a/iceprotocol.go b/iceprotocol.go
index 3582b683011..67254f7d2f5 100644
--- a/iceprotocol.go
+++ b/iceprotocol.go
@@ -13,8 +13,11 @@ import (
 type ICEProtocol int
 
 const (
+	// ICEProtocolUnknown is the enum's zero-value
+	ICEProtocolUnknown ICEProtocol = iota
+
 	// ICEProtocolUDP indicates the URL uses a UDP transport.
-	ICEProtocolUDP ICEProtocol = iota + 1
+	ICEProtocolUDP
 
 	// ICEProtocolTCP indicates the URL uses a TCP transport.
 	ICEProtocolTCP
@@ -34,7 +37,7 @@ func NewICEProtocol(raw string) (ICEProtocol, error) {
 	case strings.EqualFold(iceProtocolTCPStr, raw):
 		return ICEProtocolTCP, nil
 	default:
-		return ICEProtocol(Unknown), fmt.Errorf("%w: %s", errICEProtocolUnknown, raw)
+		return ICEProtocolUnknown, fmt.Errorf("%w: %s", errICEProtocolUnknown, raw)
 	}
 }
 
diff --git a/iceprotocol_test.go b/iceprotocol_test.go
index 428d00067d5..d2c305f8544 100644
--- a/iceprotocol_test.go
+++ b/iceprotocol_test.go
@@ -15,7 +15,7 @@ func TestNewICEProtocol(t *testing.T) {
 		shouldFail    bool
 		expectedProto ICEProtocol
 	}{
-		{unknownStr, true, ICEProtocol(Unknown)},
+		{ErrUnknownType.Error(), true, ICEProtocolUnknown},
 		{"udp", false, ICEProtocolUDP},
 		{"tcp", false, ICEProtocolTCP},
 		{"UDP", false, ICEProtocolUDP},
@@ -40,7 +40,7 @@ func TestICEProtocol_String(t *testing.T) {
 		proto          ICEProtocol
 		expectedString string
 	}{
-		{ICEProtocol(Unknown), unknownStr},
+		{ICEProtocolUnknown, ErrUnknownType.Error()},
 		{ICEProtocolUDP, "udp"},
 		{ICEProtocolTCP, "tcp"},
 	}
diff --git a/icerole.go b/icerole.go
index a46b45590f6..dce6336e9fe 100644
--- a/icerole.go
+++ b/icerole.go
@@ -8,11 +8,14 @@ package webrtc
 type ICERole int
 
 const (
+	// ICERoleUnknown is the enum's zero-value
+	ICERoleUnknown ICERole = iota
+
 	// ICERoleControlling indicates that the ICE agent that is responsible
 	// for selecting the final choice of candidate pairs and signaling them
 	// through STUN and an updated offer, if needed. In any session, one agent
 	// is always controlling. The other is the controlled agent.
-	ICERoleControlling ICERole = iota + 1
+	ICERoleControlling
 
 	// ICERoleControlled indicates that an ICE agent that waits for the
 	// controlling agent to select the final choice of candidate pairs.
@@ -32,7 +35,7 @@ func newICERole(raw string) ICERole {
 	case iceRoleControlledStr:
 		return ICERoleControlled
 	default:
-		return ICERole(Unknown)
+		return ICERoleUnknown
 	}
 }
 
diff --git a/icerole_test.go b/icerole_test.go
index fce0edd8de7..d1a2655bff7 100644
--- a/icerole_test.go
+++ b/icerole_test.go
@@ -14,7 +14,7 @@ func TestNewICERole(t *testing.T) {
 		roleString   string
 		expectedRole ICERole
 	}{
-		{unknownStr, ICERole(Unknown)},
+		{ErrUnknownType.Error(), ICERoleUnknown},
 		{"controlling", ICERoleControlling},
 		{"controlled", ICERoleControlled},
 	}
@@ -33,7 +33,7 @@ func TestICERole_String(t *testing.T) {
 		proto          ICERole
 		expectedString string
 	}{
-		{ICERole(Unknown), unknownStr},
+		{ICERoleUnknown, ErrUnknownType.Error()},
 		{ICERoleControlling, "controlling"},
 		{ICERoleControlled, "controlled"},
 	}
diff --git a/iceserver_test.go b/iceserver_test.go
index 60a27ea4329..02921f06a66 100644
--- a/iceserver_test.go
+++ b/iceserver_test.go
@@ -79,7 +79,7 @@ func TestICEServer_validate(t *testing.T) {
 				URLs:           []string{"turn:192.158.29.39?transport=udp"},
 				Username:       "unittest",
 				Credential:     false,
-				CredentialType: Unknown,
+				CredentialType: ICECredentialTypePassword,
 			}, &rtcerr.InvalidAccessError{Err: ErrTurnCredentials}},
 			{ICEServer{
 				URLs:           []string{"stun:google.de?transport=udp"},
diff --git a/icetransportpolicy.go b/icetransportpolicy.go
index a2629fdab4e..d9a41637a05 100644
--- a/icetransportpolicy.go
+++ b/icetransportpolicy.go
@@ -34,10 +34,8 @@ func NewICETransportPolicy(raw string) ICETransportPolicy {
 	switch raw {
 	case iceTransportPolicyRelayStr:
 		return ICETransportPolicyRelay
-	case iceTransportPolicyAllStr:
-		return ICETransportPolicyAll
 	default:
-		return ICETransportPolicy(Unknown)
+		return ICETransportPolicyAll
 	}
 }
 
diff --git a/icetransportstate.go b/icetransportstate.go
index fc2b62401fc..159083bb3c8 100644
--- a/icetransportstate.go
+++ b/icetransportstate.go
@@ -9,9 +9,12 @@ import "github.com/pion/ice/v3"
 type ICETransportState int
 
 const (
+	// ICETransportStateUnknown is the enum's zero-value
+	ICETransportStateUnknown ICETransportState = iota
+
 	// ICETransportStateNew indicates the ICETransport is waiting
 	// for remote candidates to be supplied.
-	ICETransportStateNew = iota + 1
+	ICETransportStateNew
 
 	// ICETransportStateChecking indicates the ICETransport has
 	// received at least one remote candidate, and a local and remote
@@ -63,7 +66,7 @@ func (c ICETransportState) String() string {
 	case ICETransportStateClosed:
 		return "closed"
 	default:
-		return unknownStr
+		return ErrUnknownType.Error()
 	}
 }
 
@@ -84,7 +87,7 @@ func newICETransportStateFromICE(i ice.ConnectionState) ICETransportState {
 	case ice.ConnectionStateClosed:
 		return ICETransportStateClosed
 	default:
-		return ICETransportState(Unknown)
+		return ICETransportStateUnknown
 	}
 }
 
@@ -105,6 +108,6 @@ func (c ICETransportState) toICE() ice.ConnectionState {
 	case ICETransportStateClosed:
 		return ice.ConnectionStateClosed
 	default:
-		return ice.ConnectionState(Unknown)
+		return ice.ConnectionStateUnknown
 	}
 }
diff --git a/icetransportstate_test.go b/icetransportstate_test.go
index a1ee930e089..324c0e40f18 100644
--- a/icetransportstate_test.go
+++ b/icetransportstate_test.go
@@ -15,7 +15,7 @@ func TestICETransportState_String(t *testing.T) {
 		state          ICETransportState
 		expectedString string
 	}{
-		{ICETransportState(Unknown), unknownStr},
+		{ICETransportStateUnknown, ErrUnknownType.Error()},
 		{ICETransportStateNew, "new"},
 		{ICETransportStateChecking, "checking"},
 		{ICETransportStateConnected, "connected"},
@@ -39,7 +39,7 @@ func TestICETransportState_Convert(t *testing.T) {
 		native ICETransportState
 		ice    ice.ConnectionState
 	}{
-		{ICETransportState(Unknown), ice.ConnectionState(Unknown)},
+		{ICETransportStateUnknown, ice.ConnectionStateUnknown},
 		{ICETransportStateNew, ice.ConnectionStateNew},
 		{ICETransportStateChecking, ice.ConnectionStateChecking},
 		{ICETransportStateConnected, ice.ConnectionStateConnected},
diff --git a/mediaengine.go b/mediaengine.go
index 2d63ab567cf..5e5a2bfdfb7 100644
--- a/mediaengine.go
+++ b/mediaengine.go
@@ -286,13 +286,12 @@ func (m *MediaEngine) RegisterFeedback(feedback RTCPFeedback, typ RTPCodecType)
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
-	switch typ {
-	case RTPCodecTypeVideo:
+	if typ == RTPCodecTypeVideo {
 		for i, v := range m.videoCodecs {
 			v.RTCPFeedback = append(v.RTCPFeedback, feedback)
 			m.videoCodecs[i] = v
 		}
-	case RTPCodecTypeAudio:
+	} else if typ == RTPCodecTypeAudio {
 		for i, v := range m.audioCodecs {
 			v.RTCPFeedback = append(v.RTCPFeedback, feedback)
 			m.audioCodecs[i] = v
diff --git a/networktype.go b/networktype.go
index 76b42465969..7169fa2efe4 100644
--- a/networktype.go
+++ b/networktype.go
@@ -22,8 +22,11 @@ func supportedNetworkTypes() []NetworkType {
 type NetworkType int
 
 const (
+	// NetworkTypeUnknown is the enum's zero-value
+	NetworkTypeUnknown NetworkType = iota
+
 	// NetworkTypeUDP4 indicates UDP over IPv4.
-	NetworkTypeUDP4 NetworkType = iota + 1
+	NetworkTypeUDP4
 
 	// NetworkTypeUDP6 indicates UDP over IPv6.
 	NetworkTypeUDP6
@@ -87,7 +90,7 @@ func NewNetworkType(raw string) (NetworkType, error) {
 	case networkTypeTCP6Str:
 		return NetworkTypeTCP6, nil
 	default:
-		return NetworkType(Unknown), fmt.Errorf("%w: %s", errNetworkTypeUnknown, raw)
+		return NetworkTypeUnknown, fmt.Errorf("%w: %s", errNetworkTypeUnknown, raw)
 	}
 }
 
@@ -102,6 +105,6 @@ func getNetworkType(iceNetworkType ice.NetworkType) (NetworkType, error) {
 	case ice.NetworkTypeTCP6:
 		return NetworkTypeTCP6, nil
 	default:
-		return NetworkType(Unknown), fmt.Errorf("%w: %s", errNetworkTypeUnknown, iceNetworkType.String())
+		return NetworkTypeUnknown, fmt.Errorf("%w: %s", errNetworkTypeUnknown, iceNetworkType.String())
 	}
 }
diff --git a/networktype_test.go b/networktype_test.go
index 213b55a9d3c..6fec764b7e9 100644
--- a/networktype_test.go
+++ b/networktype_test.go
@@ -14,7 +14,7 @@ func TestNetworkType_String(t *testing.T) {
 		cType          NetworkType
 		expectedString string
 	}{
-		{NetworkType(Unknown), unknownStr},
+		{NetworkTypeUnknown, ErrUnknownType.Error()},
 		{NetworkTypeUDP4, "udp4"},
 		{NetworkTypeUDP6, "udp6"},
 		{NetworkTypeTCP4, "tcp4"},
@@ -36,7 +36,7 @@ func TestNetworkType(t *testing.T) {
 		shouldFail   bool
 		expectedType NetworkType
 	}{
-		{unknownStr, true, NetworkType(Unknown)},
+		{ErrUnknownType.Error(), true, NetworkTypeUnknown},
 		{"udp4", false, NetworkTypeUDP4},
 		{"udp6", false, NetworkTypeUDP6},
 		{"tcp4", false, NetworkTypeTCP4},
diff --git a/peerconnection.go b/peerconnection.go
index ec2425fba6c..7b5dec14333 100644
--- a/peerconnection.go
+++ b/peerconnection.go
@@ -225,11 +225,11 @@ func (pc *PeerConnection) initConfiguration(configuration Configuration) error {
 		pc.configuration.Certificates = []Certificate{*certificate}
 	}
 
-	if configuration.BundlePolicy != BundlePolicy(Unknown) {
+	if configuration.BundlePolicy != BundlePolicyUnknown {
 		pc.configuration.BundlePolicy = configuration.BundlePolicy
 	}
 
-	if configuration.RTCPMuxPolicy != RTCPMuxPolicy(Unknown) {
+	if configuration.RTCPMuxPolicy != RTCPMuxPolicyUnknown {
 		pc.configuration.RTCPMuxPolicy = configuration.RTCPMuxPolicy
 	}
 
@@ -237,13 +237,8 @@ func (pc *PeerConnection) initConfiguration(configuration Configuration) error {
 		pc.configuration.ICECandidatePoolSize = configuration.ICECandidatePoolSize
 	}
 
-	if configuration.ICETransportPolicy != ICETransportPolicy(Unknown) {
-		pc.configuration.ICETransportPolicy = configuration.ICETransportPolicy
-	}
-
-	if configuration.SDPSemantics != SDPSemantics(Unknown) {
-		pc.configuration.SDPSemantics = configuration.SDPSemantics
-	}
+	pc.configuration.ICETransportPolicy = configuration.ICETransportPolicy
+	pc.configuration.SDPSemantics = configuration.SDPSemantics
 
 	sanitizedICEServers := configuration.getICEServers()
 	if len(sanitizedICEServers) > 0 {
@@ -549,7 +544,7 @@ func (pc *PeerConnection) SetConfiguration(configuration Configuration) error {
 	}
 
 	// https://www.w3.org/TR/webrtc/#set-the-configuration (step #5)
-	if configuration.BundlePolicy != BundlePolicy(Unknown) {
+	if configuration.BundlePolicy != BundlePolicyUnknown {
 		if configuration.BundlePolicy != pc.configuration.BundlePolicy {
 			return &rtcerr.InvalidModificationError{Err: ErrModifyingBundlePolicy}
 		}
@@ -557,7 +552,7 @@ func (pc *PeerConnection) SetConfiguration(configuration Configuration) error {
 	}
 
 	// https://www.w3.org/TR/webrtc/#set-the-configuration (step #6)
-	if configuration.RTCPMuxPolicy != RTCPMuxPolicy(Unknown) {
+	if configuration.RTCPMuxPolicy != RTCPMuxPolicyUnknown {
 		if configuration.RTCPMuxPolicy != pc.configuration.RTCPMuxPolicy {
 			return &rtcerr.InvalidModificationError{Err: ErrModifyingRTCPMuxPolicy}
 		}
@@ -574,9 +569,7 @@ func (pc *PeerConnection) SetConfiguration(configuration Configuration) error {
 	}
 
 	// https://www.w3.org/TR/webrtc/#set-the-configuration (step #8)
-	if configuration.ICETransportPolicy != ICETransportPolicy(Unknown) {
-		pc.configuration.ICETransportPolicy = configuration.ICETransportPolicy
-	}
+	pc.configuration.ICETransportPolicy = configuration.ICETransportPolicy
 
 	// https://www.w3.org/TR/webrtc/#set-the-configuration (step #11)
 	if len(configuration.ICEServers) > 0 {
@@ -879,7 +872,7 @@ func (pc *PeerConnection) setDescription(sd *SessionDescription, op stateChangeO
 	switch {
 	case pc.isClosed.get():
 		return &rtcerr.InvalidStateError{Err: ErrConnectionClosed}
-	case NewSDPType(sd.Type.String()) == SDPType(Unknown):
+	case NewSDPType(sd.Type.String()) == SDPTypeUnknown:
 		return &rtcerr.TypeError{Err: fmt.Errorf("%w: '%d' is not a valid enum value of type SDPType", errPeerConnSDPTypeInvalidValue, sd.Type)}
 	}
 
@@ -1092,7 +1085,7 @@ func (pc *PeerConnection) SetRemoteDescription(desc SessionDescription) error {
 
 			kind := NewRTPCodecType(media.MediaName.Media)
 			direction := getPeerDirection(media)
-			if kind == 0 || direction == RTPTransceiverDirection(Unknown) {
+			if kind == 0 || direction == RTPTransceiverDirectionUnknown {
 				continue
 			}
 
@@ -1292,7 +1285,7 @@ func setRTPTransceiverCurrentDirection(answer *SessionDescription, currentTransc
 		}
 
 		direction := getPeerDirection(media)
-		if direction == RTPTransceiverDirection(Unknown) {
+		if direction == RTPTransceiverDirectionUnknown {
 			continue
 		}
 
@@ -2432,7 +2425,7 @@ func (pc *PeerConnection) generateMatchedSDP(transceivers []*RTPTransceiver, use
 
 		kind := NewRTPCodecType(media.MediaName.Media)
 		direction := getPeerDirection(media)
-		if kind == 0 || direction == RTPTransceiverDirection(Unknown) {
+		if kind == 0 || direction == RTPTransceiverDirectionUnknown {
 			continue
 		}
 
diff --git a/peerconnection_js.go b/peerconnection_js.go
index 7fd1b1ca9f6..f97b2b493a3 100644
--- a/peerconnection_js.go
+++ b/peerconnection_js.go
@@ -182,14 +182,14 @@ func (pc *PeerConnection) checkConfiguration(configuration Configuration) error
 	// }
 
 	// https://www.w3.org/TR/webrtc/#set-the-configuration (step #5)
-	if configuration.BundlePolicy != BundlePolicy(Unknown) {
+	if configuration.BundlePolicy != BundlePolicyUnknown {
 		if configuration.BundlePolicy != existingConfig.BundlePolicy {
 			return &rtcerr.InvalidModificationError{Err: ErrModifyingBundlePolicy}
 		}
 	}
 
 	// https://www.w3.org/TR/webrtc/#set-the-configuration (step #6)
-	if configuration.RTCPMuxPolicy != RTCPMuxPolicy(Unknown) {
+	if configuration.RTCPMuxPolicy != RTCPMuxPolicyUnknown {
 		if configuration.RTCPMuxPolicy != existingConfig.RTCPMuxPolicy {
 			return &rtcerr.InvalidModificationError{Err: ErrModifyingRTCPMuxPolicy}
 		}
diff --git a/peerconnectionstate.go b/peerconnectionstate.go
index 1f1456882d8..9ff712112a7 100644
--- a/peerconnectionstate.go
+++ b/peerconnectionstate.go
@@ -7,11 +7,14 @@ package webrtc
 type PeerConnectionState int
 
 const (
+	// PeerConnectionStateUnknown is the enum's zero-value
+	PeerConnectionStateUnknown PeerConnectionState = iota
+
 	// PeerConnectionStateNew indicates that any of the ICETransports or
 	// DTLSTransports are in the "new" state and none of the transports are
 	// in the "connecting", "checking", "failed" or "disconnected" state, or
 	// all transports are in the "closed" state, or there are no transports.
-	PeerConnectionStateNew PeerConnectionState = iota + 1
+	PeerConnectionStateNew
 
 	// PeerConnectionStateConnecting indicates that any of the
 	// ICETransports or DTLSTransports are in the "connecting" or
@@ -62,7 +65,7 @@ func newPeerConnectionState(raw string) PeerConnectionState {
 	case peerConnectionStateClosedStr:
 		return PeerConnectionStateClosed
 	default:
-		return PeerConnectionState(Unknown)
+		return PeerConnectionStateUnknown
 	}
 }
 
diff --git a/peerconnectionstate_test.go b/peerconnectionstate_test.go
index f57ff8e0f61..27260cd9d43 100644
--- a/peerconnectionstate_test.go
+++ b/peerconnectionstate_test.go
@@ -14,7 +14,7 @@ func TestNewPeerConnectionState(t *testing.T) {
 		stateString   string
 		expectedState PeerConnectionState
 	}{
-		{unknownStr, PeerConnectionState(Unknown)},
+		{ErrUnknownType.Error(), PeerConnectionStateUnknown},
 		{"new", PeerConnectionStateNew},
 		{"connecting", PeerConnectionStateConnecting},
 		{"connected", PeerConnectionStateConnected},
@@ -37,7 +37,7 @@ func TestPeerConnectionState_String(t *testing.T) {
 		state          PeerConnectionState
 		expectedString string
 	}{
-		{PeerConnectionState(Unknown), unknownStr},
+		{PeerConnectionStateUnknown, ErrUnknownType.Error()},
 		{PeerConnectionStateNew, "new"},
 		{PeerConnectionStateConnecting, "connecting"},
 		{PeerConnectionStateConnected, "connected"},
diff --git a/rtcpmuxpolicy.go b/rtcpmuxpolicy.go
index bd68ab562ca..ec84ea91327 100644
--- a/rtcpmuxpolicy.go
+++ b/rtcpmuxpolicy.go
@@ -12,11 +12,14 @@ import (
 type RTCPMuxPolicy int
 
 const (
+	// RTCPMuxPolicyUnknown is the enum's zero-value
+	RTCPMuxPolicyUnknown RTCPMuxPolicy = iota
+
 	// RTCPMuxPolicyNegotiate indicates to gather ICE candidates for both
 	// RTP and RTCP candidates. If the remote-endpoint is capable of
 	// multiplexing RTCP, multiplex RTCP on the RTP candidates. If it is not,
 	// use both the RTP and RTCP candidates separately.
-	RTCPMuxPolicyNegotiate RTCPMuxPolicy = iota + 1
+	RTCPMuxPolicyNegotiate
 
 	// RTCPMuxPolicyRequire indicates to gather ICE candidates only for
 	// RTP and multiplex RTCP on the RTP candidates. If the remote endpoint is
@@ -37,7 +40,7 @@ func newRTCPMuxPolicy(raw string) RTCPMuxPolicy {
 	case rtcpMuxPolicyRequireStr:
 		return RTCPMuxPolicyRequire
 	default:
-		return RTCPMuxPolicy(Unknown)
+		return RTCPMuxPolicyUnknown
 	}
 }
 
diff --git a/rtcpmuxpolicy_test.go b/rtcpmuxpolicy_test.go
index 817ea82c519..66ffefae7de 100644
--- a/rtcpmuxpolicy_test.go
+++ b/rtcpmuxpolicy_test.go
@@ -14,7 +14,7 @@ func TestNewRTCPMuxPolicy(t *testing.T) {
 		policyString   string
 		expectedPolicy RTCPMuxPolicy
 	}{
-		{unknownStr, RTCPMuxPolicy(Unknown)},
+		{ErrUnknownType.Error(), RTCPMuxPolicyUnknown},
 		{"negotiate", RTCPMuxPolicyNegotiate},
 		{"require", RTCPMuxPolicyRequire},
 	}
@@ -33,7 +33,7 @@ func TestRTCPMuxPolicy_String(t *testing.T) {
 		policy         RTCPMuxPolicy
 		expectedString string
 	}{
-		{RTCPMuxPolicy(Unknown), unknownStr},
+		{RTCPMuxPolicyUnknown, ErrUnknownType.Error()},
 		{RTCPMuxPolicyNegotiate, "negotiate"},
 		{RTCPMuxPolicyRequire, "require"},
 	}
diff --git a/rtpcodec.go b/rtpcodec.go
index 69e7e07daa6..40463dcb0ce 100644
--- a/rtpcodec.go
+++ b/rtpcodec.go
@@ -13,9 +13,11 @@ import (
 type RTPCodecType int
 
 const (
+	// RTPCodecTypeUnknown is the enum's zero-value
+	RTPCodecTypeUnknown RTPCodecType = iota
 
 	// RTPCodecTypeAudio indicates this is an audio codec
-	RTPCodecTypeAudio RTPCodecType = iota + 1
+	RTPCodecTypeAudio
 
 	// RTPCodecTypeVideo indicates this is a video codec
 	RTPCodecTypeVideo
diff --git a/rtptransceiver.go b/rtptransceiver.go
index 02ddf79243b..15d28f720d1 100644
--- a/rtptransceiver.go
+++ b/rtptransceiver.go
@@ -42,7 +42,7 @@ func newRTPTransceiver(
 	t.setReceiver(receiver)
 	t.setSender(sender)
 	t.setDirection(direction)
-	t.setCurrentDirection(RTPTransceiverDirection(Unknown))
+	t.setCurrentDirection(RTPTransceiverDirectionUnknown)
 	return t
 }
 
@@ -193,7 +193,7 @@ func (t *RTPTransceiver) getCurrentDirection() RTPTransceiverDirection {
 	if v, ok := t.currentDirection.Load().(RTPTransceiverDirection); ok {
 		return v
 	}
-	return RTPTransceiverDirection(Unknown)
+	return RTPTransceiverDirectionUnknown
 }
 
 func (t *RTPTransceiver) setSendingTrack(track TrackLocal) error {
diff --git a/rtptransceiverdirection.go b/rtptransceiverdirection.go
index 752cd5b9c6c..5e1a5be1bc7 100644
--- a/rtptransceiverdirection.go
+++ b/rtptransceiverdirection.go
@@ -7,9 +7,12 @@ package webrtc
 type RTPTransceiverDirection int
 
 const (
+	// RTPTransceiverDirectionUnknown is the enum's zero-value
+	RTPTransceiverDirectionUnknown RTPTransceiverDirection = iota
+
 	// RTPTransceiverDirectionSendrecv indicates the RTPSender will offer
 	// to send RTP and the RTPReceiver will offer to receive RTP.
-	RTPTransceiverDirectionSendrecv RTPTransceiverDirection = iota + 1
+	RTPTransceiverDirectionSendrecv
 
 	// RTPTransceiverDirectionSendonly indicates the RTPSender will offer
 	// to send RTP.
@@ -45,7 +48,7 @@ func NewRTPTransceiverDirection(raw string) RTPTransceiverDirection {
 	case rtpTransceiverDirectionInactiveStr:
 		return RTPTransceiverDirectionInactive
 	default:
-		return RTPTransceiverDirection(Unknown)
+		return RTPTransceiverDirectionUnknown
 	}
 }
 
diff --git a/rtptransceiverdirection_test.go b/rtptransceiverdirection_test.go
index c8a8da0ec45..78c6899532c 100644
--- a/rtptransceiverdirection_test.go
+++ b/rtptransceiverdirection_test.go
@@ -14,7 +14,7 @@ func TestNewRTPTransceiverDirection(t *testing.T) {
 		directionString   string
 		expectedDirection RTPTransceiverDirection
 	}{
-		{unknownStr, RTPTransceiverDirection(Unknown)},
+		{ErrUnknownType.Error(), RTPTransceiverDirectionUnknown},
 		{"sendrecv", RTPTransceiverDirectionSendrecv},
 		{"sendonly", RTPTransceiverDirectionSendonly},
 		{"recvonly", RTPTransceiverDirectionRecvonly},
@@ -35,7 +35,7 @@ func TestRTPTransceiverDirection_String(t *testing.T) {
 		direction      RTPTransceiverDirection
 		expectedString string
 	}{
-		{RTPTransceiverDirection(Unknown), unknownStr},
+		{RTPTransceiverDirectionUnknown, ErrUnknownType.Error()},
 		{RTPTransceiverDirectionSendrecv, "sendrecv"},
 		{RTPTransceiverDirectionSendonly, "sendonly"},
 		{RTPTransceiverDirectionRecvonly, "recvonly"},
diff --git a/sctptransportstate.go b/sctptransportstate.go
index 5dd51d6f5d6..9deb73813ed 100644
--- a/sctptransportstate.go
+++ b/sctptransportstate.go
@@ -7,10 +7,13 @@ package webrtc
 type SCTPTransportState int
 
 const (
+	// SCTPTransportStateUnknown is the enum's zero-value
+	SCTPTransportStateUnknown SCTPTransportState = iota
+
 	// SCTPTransportStateConnecting indicates the SCTPTransport is in the
 	// process of negotiating an association. This is the initial state of the
 	// SCTPTransportState when an SCTPTransport is created.
-	SCTPTransportStateConnecting SCTPTransportState = iota + 1
+	SCTPTransportStateConnecting
 
 	// SCTPTransportStateConnected indicates the negotiation of an
 	// association is completed.
@@ -39,7 +42,7 @@ func newSCTPTransportState(raw string) SCTPTransportState {
 	case sctpTransportStateClosedStr:
 		return SCTPTransportStateClosed
 	default:
-		return SCTPTransportState(Unknown)
+		return SCTPTransportStateUnknown
 	}
 }
 
diff --git a/sctptransportstate_test.go b/sctptransportstate_test.go
index c97f277c7a9..59b6d52b1ee 100644
--- a/sctptransportstate_test.go
+++ b/sctptransportstate_test.go
@@ -14,7 +14,7 @@ func TestNewSCTPTransportState(t *testing.T) {
 		transportStateString   string
 		expectedTransportState SCTPTransportState
 	}{
-		{unknownStr, SCTPTransportState(Unknown)},
+		{ErrUnknownType.Error(), SCTPTransportStateUnknown},
 		{"connecting", SCTPTransportStateConnecting},
 		{"connected", SCTPTransportStateConnected},
 		{"closed", SCTPTransportStateClosed},
@@ -34,7 +34,7 @@ func TestSCTPTransportState_String(t *testing.T) {
 		transportState SCTPTransportState
 		expectedString string
 	}{
-		{SCTPTransportState(Unknown), unknownStr},
+		{SCTPTransportStateUnknown, ErrUnknownType.Error()},
 		{SCTPTransportStateConnecting, "connecting"},
 		{SCTPTransportStateConnected, "connected"},
 		{SCTPTransportStateClosed, "closed"},
diff --git a/sdp.go b/sdp.go
index 0622c759011..0cd61873d3f 100644
--- a/sdp.go
+++ b/sdp.go
@@ -653,11 +653,11 @@ func descriptionPossiblyPlanB(desc *SessionDescription) bool {
 
 func getPeerDirection(media *sdp.MediaDescription) RTPTransceiverDirection {
 	for _, a := range media.Attributes {
-		if direction := NewRTPTransceiverDirection(a.Key); direction != RTPTransceiverDirection(Unknown) {
+		if direction := NewRTPTransceiverDirection(a.Key); direction != RTPTransceiverDirectionUnknown {
 			return direction
 		}
 	}
-	return RTPTransceiverDirection(Unknown)
+	return RTPTransceiverDirectionUnknown
 }
 
 func extractFingerprint(desc *sdp.SessionDescription) (string, string, error) {
diff --git a/sdpsemantics.go b/sdpsemantics.go
index 6d63350477a..689b4e95bf5 100644
--- a/sdpsemantics.go
+++ b/sdpsemantics.go
@@ -36,14 +36,12 @@ const (
 
 func newSDPSemantics(raw string) SDPSemantics {
 	switch raw {
-	case sdpSemanticsUnifiedPlan:
-		return SDPSemanticsUnifiedPlan
 	case sdpSemanticsPlanB:
 		return SDPSemanticsPlanB
 	case sdpSemanticsUnifiedPlanWithFallback:
 		return SDPSemanticsUnifiedPlanWithFallback
 	default:
-		return SDPSemantics(Unknown)
+		return SDPSemanticsUnifiedPlan
 	}
 }
 
diff --git a/sdpsemantics_test.go b/sdpsemantics_test.go
index d513c3b994c..eff518f7321 100644
--- a/sdpsemantics_test.go
+++ b/sdpsemantics_test.go
@@ -29,7 +29,7 @@ func TestSDPSemantics_String(t *testing.T) {
 	}
 
 	assert.Equal(t,
-		unknownStr,
+		ErrUnknownType.Error(),
 		SDPSemantics(42).String(),
 	)
 
diff --git a/sdptype.go b/sdptype.go
index 0c6d1d4649c..5aa3b986116 100644
--- a/sdptype.go
+++ b/sdptype.go
@@ -12,9 +12,11 @@ import (
 type SDPType int
 
 const (
-	// SDPTypeOffer indicates that a description MUST be treated as an SDP
-	// offer.
-	SDPTypeOffer SDPType = iota + 1
+	// SDPTypeUnknown is the enum's zero-value
+	SDPTypeUnknown SDPType = iota
+
+	// SDPTypeOffer indicates that a description MUST be treated as an SDP offer.
+	SDPTypeOffer
 
 	// SDPTypePranswer indicates that a description MUST be treated as an
 	// SDP answer, but not a final answer. A description used as an SDP
@@ -56,7 +58,7 @@ func NewSDPType(raw string) SDPType {
 	case sdpTypeRollbackStr:
 		return SDPTypeRollback
 	default:
-		return SDPType(Unknown)
+		return SDPTypeUnknown
 	}
 }
 
diff --git a/sdptype_test.go b/sdptype_test.go
index 40daedf127e..9f045d18608 100644
--- a/sdptype_test.go
+++ b/sdptype_test.go
@@ -14,7 +14,7 @@ func TestNewSDPType(t *testing.T) {
 		sdpTypeString   string
 		expectedSDPType SDPType
 	}{
-		{unknownStr, SDPType(Unknown)},
+		{ErrUnknownType.Error(), SDPTypeUnknown},
 		{"offer", SDPTypeOffer},
 		{"pranswer", SDPTypePranswer},
 		{"answer", SDPTypeAnswer},
@@ -35,7 +35,7 @@ func TestSDPType_String(t *testing.T) {
 		sdpType        SDPType
 		expectedString string
 	}{
-		{SDPType(Unknown), unknownStr},
+		{SDPTypeUnknown, ErrUnknownType.Error()},
 		{SDPTypeOffer, "offer"},
 		{SDPTypePranswer, "pranswer"},
 		{SDPTypeAnswer, "answer"},
diff --git a/sessiondescription_test.go b/sessiondescription_test.go
index d9eb2580153..c167d0d10f0 100644
--- a/sessiondescription_test.go
+++ b/sessiondescription_test.go
@@ -21,7 +21,7 @@ func TestSessionDescription_JSON(t *testing.T) {
 		{SessionDescription{Type: SDPTypePranswer, SDP: "sdp"}, `{"type":"pranswer","sdp":"sdp"}`, nil},
 		{SessionDescription{Type: SDPTypeAnswer, SDP: "sdp"}, `{"type":"answer","sdp":"sdp"}`, nil},
 		{SessionDescription{Type: SDPTypeRollback, SDP: "sdp"}, `{"type":"rollback","sdp":"sdp"}`, nil},
-		{SessionDescription{Type: SDPType(Unknown), SDP: "sdp"}, `{"type":"unknown","sdp":"sdp"}`, ErrUnknownType},
+		{SessionDescription{Type: SDPTypeUnknown, SDP: "sdp"}, `{"type":"unknown","sdp":"sdp"}`, ErrUnknownType},
 	}
 
 	for i, testCase := range testCases {
diff --git a/signalingstate.go b/signalingstate.go
index ebbf7542cbd..9d60afd2601 100644
--- a/signalingstate.go
+++ b/signalingstate.go
@@ -32,10 +32,13 @@ func (op stateChangeOp) String() string {
 type SignalingState int32
 
 const (
+	// SignalingStateUnknown is the enum's zero-value
+	SignalingStateUnknown SignalingState = iota
+
 	// SignalingStateStable indicates there is no offer/answer exchange in
 	// progress. This is also the initial state, in which case the local and
 	// remote descriptions are nil.
-	SignalingStateStable SignalingState = iota + 1
+	SignalingStateStable
 
 	// SignalingStateHaveLocalOffer indicates that a local description, of
 	// type "offer", has been successfully applied.
@@ -84,7 +87,7 @@ func newSignalingState(raw string) SignalingState {
 	case signalingStateClosedStr:
 		return SignalingStateClosed
 	default:
-		return SignalingState(Unknown)
+		return SignalingStateUnknown
 	}
 }
 
diff --git a/signalingstate_test.go b/signalingstate_test.go
index 140e20f7a36..1708d316a24 100644
--- a/signalingstate_test.go
+++ b/signalingstate_test.go
@@ -15,7 +15,7 @@ func TestNewSignalingState(t *testing.T) {
 		stateString   string
 		expectedState SignalingState
 	}{
-		{unknownStr, SignalingState(Unknown)},
+		{ErrUnknownType.Error(), SignalingStateUnknown},
 		{"stable", SignalingStateStable},
 		{"have-local-offer", SignalingStateHaveLocalOffer},
 		{"have-remote-offer", SignalingStateHaveRemoteOffer},
@@ -38,7 +38,7 @@ func TestSignalingState_String(t *testing.T) {
 		state          SignalingState
 		expectedString string
 	}{
-		{SignalingState(Unknown), unknownStr},
+		{SignalingStateUnknown, ErrUnknownType.Error()},
 		{SignalingStateStable, "stable"},
 		{SignalingStateHaveLocalOffer, "have-local-offer"},
 		{SignalingStateHaveRemoteOffer, "have-remote-offer"},