[OpenSIPS-Users] Registrant & LB with SRV

[Walter Schober]

Hello Antonis!

IMHO the carrier cannot expect Register and Invite going to the same destination if the SRV for _the_ service is load-balanced.

We do offer such a service as carrier also but encountered the issue with LB on nearly every device, incl. phones. Since we also need the call to be established across the same service endpoint selected in the Register process we set priorities on each SRV for each datacenter.
For such cases we do additionally name two A records where the endpoint must register on both and then can do LB calls to each. Otherwise the carriers service must allow registers and invites going different ways. It is **one** service based on the SRV entry!

Br
Walter

Von: Users <users-bounces at lists.opensips.org> Im Auftrag von Antonios Psaras
Gesendet: Freitag, 20. Juni 2025 11:24
An: 'OpenSIPS users mailling list' <users at lists.opensips.org>
Betreff: [OpenSIPS-Users] Registrant & LB with SRV

Hello Team

I have the following situation.

A telecom carrier requires SIP Registration prior to Dial out using SIP Domain and SRV Lookup.

To achieve that I am using registrant module and load balancing module.

The problem I have, is that in some cases registrant registers on different SBC of the Carrier than the one resolved by Load Balancer Module so my outbound calls are failing with 407.

I have two thoughts but I do not know how to implement any of those.


  1.  Instead of using LB Modules, I will some how get the registrar IP from registrant module and statically route the calls through that. Is there a way to get that information from registrant module?
  2.  DNS lookup is done automatically only in case of 503 or timeout. Is there a way to force DNS lookup with in OpenSIP Script? If yes I can handle 407, force DNS Lookup, create a new branch and re-send the call.

Any other thoughts are welcome

Best regards

Antonis Psaras

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