Hello dear Kamailio Community. I am faced with the problem. Kamailio perfectly copes with ims server task. But 5 phone call does not work. I used the sngrep to track traffic, found that on the 5th call, instead of UPDATE, there is a CANCEL with Reason: RELEASE_CAUSE ;cause=3 ;text="Media bearer loss". All packets from the start of the call are the same up to this point.

Here is a detailed description of the normal call and bad call package.

Normal call package ``` 2022/07/04 08:55:04.887359 192.168.101.3:5060 -> 172.22.0.21:5060 UPDATE sip:1337@192.168.101.2:7700;alias=192.168.101.2~7700~2 SIP/2.0 Max-Forwards: 70 To: tel:1337;phone-context=ims.mnc001.mcc001.3gppnetwork.org;tag=aa64262d From: sip:1339@ims.mnc001.mcc001.3gppnetwork.org;tag=908707735 Call-ID: 908707729_2065538424@192.168.101.3 CSeq: 908707731 UPDATE P-Access-Network-Info: 3GPP-E-UTRAN-FDD; utran-cell-id-3gpp=0010100010019B01 Content-Length: 463 Via: SIP/2.0/TCP 192.168.101.3:5060;branch=z9hG4bK495826873 Route: sip:mo@172.22.0.21;transport=tcp;r2=on;lr=on;ftag=908707735;rm=8;did=e99.70a,sip:mo@172.22.0.21;r2=on;lr=on;ftag=908707735;rm=8;did=e99.70a,sip:mo@172.22.0.20:6060;transport cp;r2=on;lr=on;ftag=908707735;did=e99.83e1,sip:mo@172.22.0.20:6060;r2=on;lr=on;ftag=908707735;did=e99.83e1,sip:mt@172.22.0.20:6060;lr=on;ftag=908707735;did=e99.93e1,sip:mt@172.22. 21;r2=on;lr=on;ftag=908707735;rm=7;did=e99.80a,sip:mt@172.22.0.21:5100;transport=tcp;r2=on;lr=on;ftag=908707735;rm=7;did=e99.80a Allow: INVITE,ACK,CANCEL,BYE,UPDATE,PRACK,MESSAGE,REFER,NOTIFY,INFO,OPTIONS User-Agent: XXXX Content-Type: application/sdp Require: precondition Contact: sip:XXXX@192.168.101.3:5060;+g.3gpp.icsi-ref="urn%3Aurn-7%3A3gpp-service.ims.icsi.mmtel";audio;video ```

Broken Call Package ``` 2022/07/04 08:55:21.187316 192.168.101.3:5060 -> 172.22.0.21:5060 CANCEL tel:1337;phone-context=ims.mnc001.mcc001.3gppnetwork.org SIP/2.0 Content-Length: 453 Content-Type: application/sdp Reason: RELEASE_CAUSE ;cause=3 ;text="Media bearer loss" From: sip:1339@ims.mnc001.mcc001.3gppnetwork.org;tag=908718152 To: tel:1337;phone-context=ims.mnc001.mcc001.3gppnetwork.org Call-ID: 908718145_2063316408@192.168.101.3 Max-Forwards: 70 CSeq: 908718145 CANCEL Via: SIP/2.0/TCP 192.168.101.3:5060;branch=z9hG4bK1317538702;rport=5060 Route: sip:172.22.0.21:5060;lr,sip:orig@scscf.ims.mnc001.mcc001.3gppnetwork.org:6060;lr User-Agent: XXXX ```

I was looking for the reason in p-cscf, but I came to a dead end. Please tell me what the reasons for this "Media bearer loss" may be or what documentation is worth reading. I didn't find anything on the official documentation