Yes, integrating Retell AI with FreePBX/Asterisk is possible. Retell AI supports custom telephony providers via SIP.(1)
Documentation for Generic SIP Trunk Integration
For generic SIP trunk providers, you can find comprehensive documentation at the Custom Telephony Overview.(1)
Two Integration Methods
Retell AI provides two ways to integrate with your telephony provider:(1)
1. Elastic SIP Trunking (Recommended)(1)
This is the recommended way to integrate with telephony providers that support elastic SIP trunking.(1) You’ll need to set up a SIP trunk and configure your number to point to it, then import that number to Retell.(1)
2. Dial to SIP URI(1)
If your telephony provider doesn’t support elastic SIP trunking, or you have more complicated telephony setup, you can dial the call to a specific SIP URI.(1)
Retell SIP Server Details
- Retell SIP server URI:
sip:sip.retellai.com(1) - IP block for traffic:
18.98.16.120/30(All regions),143.223.88.0/21(certain United States traffic),161.115.160.0/19(certain United States traffic)(1)
Transport Methods Supported
For different transport methods for inbound calls:(1)
- For TCP:
sip:sip.retellai.com;transport=tcp(1) - For UDP:
sip:sip.retellai.com;transport=udp(1) - For TLS:
sip:sip.retellai.com;transport=tls(1)
Media Encryption
SRTP is supported (Transport should be set to TLS to use SRTP).(1)
Additional Resources
The documentation also provides detailed guides for specific telephony providers like Twilio, Telnyx, and Vonage, which you can use as references for your FreePBX/Asterisk setup.(1)