Failed to connect outbound calls through Yeastar P570 IP PBX — SIP timeout even without IP whitelisting

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1

Agent ID1: agent_5f63b1a5d993b27356649860c5
Agent ID2: agent_823d0ccc74fe56333a292d0541

If we want to integrate with a Yeastar P570 IP PBX, are there any successful case studies or examples for this? We’ve been trying to use an IP PBX as the intermediary device for integration (with no IP restrictions at all), but still haven’t been able to connect successfully. Are there any known limitations or requirements we should be aware of?

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Hi @chrischen

For integrating any custom PBX, the general guidance applies:

Requirements from /deploy/custom-telephony:

  • Retell SIP server: sip:sip.retellai.com

  • Transport: TCP (recommended), UDP, TLS, or mTLS

  • Codecs: PCMU, PCMA, G.722

  • Media encryption: SRTP (requires TLS)

  • Retell’s IP blocks (for whitelisting on your PBX side): 18.98.16.120/30, 143.223.88.0/21, 161.115.160.0/19

Your log shows sip request timed out / dial_no_answer , check your PBX termination/routing settings and logs.

For complex PBX setups that don’t cleanly support elastic SIP trunking, consider Dial to SIP URI, or use a telephony partner like Jambonz or Cloudonix to bridge your PBX to Retell.

Could you please share the call ID along with the PCAP file? This will help our team take a closer look and investigate the issue.

Thank You