To overcome what Alex described, PATH module provides a simple but powerful solution to be used in intermediary proxies. In such a scenario, Kamailio only forwards Registrations.

https://kamailio.org/docs/modules/5.1.x/modules/path.html

For the other option, have a look at the famous example: http://kb.asipto.com/asterisk:realtime:kamailio-4.0.x-asterisk-11.3.0-astdb

About use of PJSIP, I've had my part of disappointments and inconsistencies when it comes to integration with an edge proxy, hope others have more luck.

On Tue, May 29, 2018 at 1:57 PM, Alex Balashov <abalashov@evaristesys.com> wrote:
On Tue, May 29, 2018 at 05:55:07PM +0000, Wilkins, Steve wrote:

> Who forwards Registrations to Asterisk or PBX, and who lets Kamailio
> maintain Registrations?

That all depends on what you're trying to accomplish.

But one historical problem with Asterisk has been that Dial()ing peers
through a trunk sip.conf peer to reach them via a centralised registrar
broke certain Class 5 features (MWI, presence stuff) that relied on
contact bindings being in local AstDB.

As I understand it, the new chan_pjsip driver has effectively vanquished
that problem, so it makes no difference if your registrar is outboard or
internal.

--
Alex Balashov | Principal | Evariste Systems LLC

Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/

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