diff --git a/internal/sms-gateway/handlers/3rdparty.go b/internal/sms-gateway/handlers/3rdparty.go
index e59563e7..67b73bff 100644
--- a/internal/sms-gateway/handlers/3rdparty.go
+++ b/internal/sms-gateway/handlers/3rdparty.go
@@ -47,7 +47,8 @@ func (h *thirdPartyHandler) postMessage(user models.User, c *fiber.Ctx) error {
 	device := user.Devices[0]
 	state, err := h.messagesSvc.Enqeue(device, req)
 	if err != nil {
-		if errors.Is(err, services.ErrValidation) {
+		var err400 services.ErrValidation
+		if errors.As(err, &err400) {
 			return fiber.NewError(fiber.StatusBadRequest, err.Error())
 		}
 
diff --git a/internal/sms-gateway/services/messages.go b/internal/sms-gateway/services/messages.go
index 3b802374..38b2472f 100644
--- a/internal/sms-gateway/services/messages.go
+++ b/internal/sms-gateway/services/messages.go
@@ -3,7 +3,6 @@ package services
 import (
 	"context"
 	"crypto/sha256"
-	"errors"
 	"fmt"
 	"log"
 	"time"
@@ -21,7 +20,11 @@ const (
 	ErrorTTLExpired = "TTL expired"
 )
 
-var ErrValidation error = errors.New("validation error")
+type ErrValidation string
+
+func (e ErrValidation) Error() string {
+	return string(e)
+}
 
 type MessagesService struct {
 	Messages *repositories.MessagesRepository
@@ -254,14 +257,16 @@ func modelToRecipientState(input models.MessageRecipient) smsgateway.RecipientSt
 func cleanPhoneNumber(input string) (string, error) {
 	phone, err := phonenumbers.Parse(input, "RU")
 	if err != nil {
-		return input, fmt.Errorf("can't parse phone number: %w", err)
+		return input, ErrValidation(fmt.Sprintf("can't parse phone number: %s", err.Error()))
 	}
+
 	if !phonenumbers.IsValidNumber(phone) {
-		return input, fmt.Errorf("invalid phone number")
+		return input, ErrValidation("invalid phone number")
 	}
+
 	phoneNumberType := phonenumbers.GetNumberType(phone)
 	if phoneNumberType != phonenumbers.MOBILE && phoneNumberType != phonenumbers.FIXED_LINE_OR_MOBILE {
-		return input, fmt.Errorf("not mobile phone number")
+		return input, ErrValidation("not mobile phone number")
 	}
 
 	return phonenumbers.Format(phone, phonenumbers.E164), nil