Custom SIP outbound: static egress IP and Retell-issued SIP credentials

Support Help
1

Hi Retell team — Cadena (workspace: Cadena; sid@cadena.ae) is connecting an elastic SIP trunk to Maqsam for UAE +971 CLI outbound using Option 2 Direct Outbound.

Maqsam requires:

  1. one specific static Retell egress IP to whitelist (they cannot whitelist all Retell CIDR ranges); and

  2. SIP username/password issued by Retell for Retell to send INVITEs to 3.70.34.179.

Can Retell provide or pin one static egress IP for our workspace? Does Retell issue SIP username/password for outbound to a third-party termination URI, or is the supported model only provider-issued credentials and/or whitelisting Retell’s published CIDRs?

If neither is possible, please confirm the only supported path is whitelisting published CIDRs and/or provider-issued trunk auth, and include the published CIDRs as plain text (no http).

No changes to billing, agents, or numbers are requested. Thanks!

2

Hey @sid

Retell doesn’t offer a single pinned static egress IP, and there’s no Retell-issued SIP username/password for dialing out to a third-party termination URI. The only supported outbound model is:

  1. Whitelist Retell’s published CIDR blocks on Maqsam’s trunk ACL, and/or
  2. Use provider-issued (Maqsam-issued) SIP trunk credentials, which you supply to Retell when importing the number (sip_trunk_auth_username / sip_trunk_auth_password).

Retell has no termination SIP URI of its own — sip:sip.retellai.com is only used for inbound origination. For outbound, Retell sends INVITEs from its egress ranges to whatever termination URI/credentials you configure. Published CIDR blocks (plain text):

18.98.16.120/30
3.42.144.0/23
153.57.128.0/18
143.223.88.0/21
161.115.160.0/19

(Last two are for certain United States traffic; the first three apply to all regions.)

If Maqsam can only whitelist one IP and cannot accept a CIDR range or username/password auth, that combination isn’t supported today — Retell’s egress isn’t pinned to a single IP.

Best Regards.