v2.2.0-beta — Inbound Voice AI Infrastructure

This release focuses on three infrastructure changes that make inbound voice AI production-ready.

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Breaking change: transfer_to replaces to in transfer tool calls. Update your configs before upgrading.

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Distributed SIP Registration

The registration flow is now based on explicit ownership and reconciliation:

• Each DID is claimed through Redis-backed ownership
• One instance becomes the active owner for that DID
• The owner performs SIP registration and keeps it active
• If that owner disappears, another instance can claim the DID and restore service

This is a key step toward making inbound voice AI reliable in multi-instance deployments.

Multi-Server Ownership and Failover

The registration pipeline now separates ownership, registration, and active-state handling more cleanly:

• Clearer ownership semantics per DID
• Safer failover across replicas
• Fewer single-node assumptions
• More predictable behavior in horizontally scaled deployments

Multi-Target SIP Transfer Failover

SIP transfer now supports multiple ordered transfer_to targets:

• Try target 1
• If target 1 fails or does not answer, try target 2
• Continue until a target connects or the list is exhausted

Defined Post-Transfer Behavior

Transfer now has explicit post-transfer behavior for SIP:

• end_call
• resume_ai

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Engineer-Facing Changelog

SIP Registration

• Added distributed SIP registration manager
• Added Redis-backed DID ownership flow
• Added multi-server registration pipeline
• Separated claim ownership, register, and mark-active stages
• Improved reconcile behavior for active and removed registrations
• Improved ownership release behavior for failover and cleanup

SIP Transfer

• Added support for ordered multi-target transfer via transfer_to
• Added per-target transfer retry/failover flow
• Added explicit post-transfer behavior with end_call and resume_ai
• Improved transfer handling in SIP pipeline and streamer path
• Aligned transfer behavior for channels where multi-target transfer does not apply

Telephony and Session Behavior

• Improved metadata alignment across telephony paths
• Improved transfer-related session state handling
• Improved observer/event behavior around transfer lifecycle
• Reduced undefined behavior after operator hangup

Tooling and API Cleanup

• Renamed transfer argument from to to transfer_to
• Improved transfer tool call handling
• Improved downstream transfer orchestration consistency

Stability and Tests

• Added and updated tests around transfer behavior
• Improved dispatch-related test coverage
• Fixed call-flow edge cases around tool calls and injected messages
• Refined dispatch behavior for transfer and tool-call flows

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Full Changelog: v2.1.0...v2.2.0