This question probably belongs in the asterisk forum, but here’s a quick answer:

It’s most likely a reINVITE in order to modify the existing session. Compare it to the original and see if anything has changed (like the codecs in the SDP).

Med vennlig hilsen
Pan B. Christensen
Utvikler
Phonect AS

From: sr-users <sr-users-bounces@lists.kamailio.org> On Behalf Of Wilkins, Steve
Sent: onsdag 13. juni 2018 12:47
To: Kamailio (SER) - Users Mailing List <sr-users@lists.kamailio.org>
Subject: [SR-Users] Asterisk inviting Kamailio

Hello All,

I have noticed that sometimes when a call is made from one endpoint to another through Asterisk via Kamailio, Asterisk sends an INVITE to Kamailio even after the call has been established.  Sometimes this does not happen.   When it does happen, calls drop.

Why would an INVITE be sent back to Kamailio?

Also, Pan, I am working on the response you requested yesterday.

Thanks you All,

-Steve