Inbound BYOT SIP (Twilio): calls match trunk but always return 486 Busy, no room created

Telephony
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1

Inbound BYOT SIP (Twilio): calls return 486 Busy, no rooms created

I’m using Twilio BYOT SIP with inbound trunk configured for a phone number.

Configuration:

  • SIP Endpoint: sip:[projectid].sip.livekit.cloud
  • Inbound trunk: configured with E.164 phone number, no auth
  • Dispatch rule: Individual (Caller) mode with room prefix
  • Agent: Registered and running

Problem:

  • Calls to the configured number → 486 Busy error
  • No rooms created, agent never receives session
  • Both real calls and API test calls fail identically

Tested:

  • E.164 format ✓
  • Correct SIP URI ✓
  • No auth config ✓
  • IP allowlist ✓

What could cause the trunk to reject calls before reaching dispatch rules?

2

Where do you see the 486? I don’t see that the call is reaching LiveKit. 486 is typically an agent issue (it can’t pick up) but if I call your number, I don’t see any activity.

I think the issue might be your SIP endpoint config when creating your Twilio trunk, Create and configure a Twilio SIP trunk | LiveKit Documentation. The SIP URL should be as found in your project settings (here), not the format you gave above.