Caik_Rian
06/16/2025, 5:44 PMVapi Support Bot
06/16/2025, 5:46 PMcall.in-progress.error-sip-outbound-call-failed-to-connect means the SIP provider failed to connect the outbound call. Since you've already allowlisted the required Vapi IPs, the next best step is to confirm with your SIP provider whether there are any rate limits or concurrent call restrictions in place that could be causing these failures during simultaneous call attempts. If the issue persists, please contact Vapi support with your call code for deeper investigation, as this type of instability may require backend review and is a known intermittent issue in some environments ([Vapi documentation](https://docs.vapi.ai/calls/call-ended-reason)).
Sources:
- [Call ended reasons (Vapi documentation)](https://docs.vapi.ai/calls/call-ended-reason)
- [SIP trunking and network requirements (Vapi documentation)](https://docs.vapi.ai/advanced/sip/sip-trunk)
- [Vapi Discord support thread](https://discord.com/channels/1211482211119796234/1372358449761091584)Caik_Rian
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