iPhone does not send INVITE when making a call

[ktsubouc]

Dear all,

I am testing 4G VoLTE call by docker_open5gs.
I confirmed that Android phone can make calls with each other.
However iPhone (I tested iPhone SE3, iPhone 12, iPhone 13, iPhone 15) cannot make calls. Specifically speaking, iPhone registers/subscribes to IMS, but it does not send INVITE message when it makes a call. On a side note, I observed iPhone replied with "486 Establising Another Call" to OPTIONS message while iPhone was making a call.
Interestingly, iPhone can receive calls from Android.
Any idea to solve this issue?

Many thanks in advance!
Koji

[herlesupreeth]

Try changing tcp_connection_lifetime to 1 in kamailio_pcscf.cfg file under pcscf folder and restart P-CSCF

[herlesupreeth]

Then, please attach a pcap of scenario where you register the iPhone to network and followed by it try to place a call.

[ktsubouc]

docker_open5gs_call_log_sip_only_2024-07-17.pcapng.zip

pcap is attached. this was taken at S1 interface.

id:8111000100101 - iPhone12
id:8111000100102 - Android phone

[ktsubouc]

You will see "486 Establishing Another Call" e.g. frame#46 when I was making a call from iPhone.

[herlesupreeth]

Thanks for the pcap. But sadly I couldnt narrow down why there is 486 Establishing Another Call. One thing you can try is to disable NAT ping (using SIP OPTIONS)

change #!define WITH_NATPING to ##!define WITH_NATPING in pcscf.cfg

[ktsubouc]

Thanks for replying and sorry for not responding for a while. I have just tested with the latest build by disabling NAT ping, but it did not work.

[ajrise]

This is a call I made through iPhone XSMax, it's send the Invite normally

[ktsubouc]

Thanks, which version are you using? I am using the latest one. The pcap taken was done by the version downloaded today, but I have been struggling with this issue for a couple of weeks.

[ajrise]

It's IOS17.2.1