### Answer Based on the available sources, here's what I can confirm about connecting Retell AI with Jambonz and 3CX: ## Jambonz Overview Jambonz is an open-source CPaaS designed for communications service providers that enables seamless connectivity to custom telephony systems via SIP trunking. [(1) ]() ## Resources Available For Jambonz + Retell AI integration: - There's a dedicated tutorial: [Using jambonz for telephony integration with Retell AI]() For 3CX integration: - Retell AI has a 3CX integration manual available under "telephony products" [(2) ]() ## Support Channels - Jambonz offers a dedicated Slack support channel for Retell users at the

#retellai-bof

channel (get an invite at [(1) ]() ## Important Considerations When connecting a PBX to Retell via Jambonz, be aware that internal extension numbers (like "001") won't work directly—Retell requires E.164 formatted phone numbers. You may need to modify your Jambonz app or routing logic to translate internal extensions into valid E.164 Caller IDs before sending to Retell. [(3) ]() I don't have complete step-by-step instructions in the available sources. For detailed setup guidance, I recommend: - Following the Jambonz blog tutorial linked above - Consulting the 3CX integration manual in Retell's telephony products section - Joining the Jambonz Slack for Retell-specific configuration help Would you like me to try to provide a general answer based on my knowledge, or would you prefer to check those resources directly?

​ To learn more, see the sources I considered: [[1] Jambonz | Retell AI APP Partner](https://www.retellai.com/app-partner/jambonz) [[2] Smarter Call Transfers with Alex & Nir (Cloudonix)]() [[3] custom telephony extension PBX to retell](https://discord.com/channels/1186424376300679209/1346173542873432084) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.