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

**URL:** <https://community.retellai.com/t/custom-sip-outbound-static-egress-ip-and-retell-issued-sip-credentials/3625>\
**Category:** Support Help\
**Tags:** telephony\
**Created:** [September 8, 2026, 2:16am UTC](https://community.retellai.com/t/custom-sip-outbound-static-egress-ip-and-retell-issued-sip-credentials/3625 "2026-09-08T02:16:15Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![sid](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/sid/32/2691_2.png) [@sid](https://community.retellai.com/u/sid)\
**Post date:** [September 8, 2026, 2:16am UTC](https://community.retellai.com/t/custom-sip-outbound-static-egress-ip-and-retell-issued-sip-credentials/3625/1 "2026-09-08T02:16:15Z")

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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!

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<div class="post-metadata">

**Author:** ![mark1](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/mark1/32/2524_2.png) [@mark1](https://community.retellai.com/u/mark1)\
**Post date:** [September 8, 2026, 12:14pm UTC](https://community.retellai.com/t/custom-sip-outbound-static-egress-ip-and-retell-issued-sip-credentials/3625/2 "2026-09-08T12:14:06Z")

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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):

```auto
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.