Aastra 6753i - no incoming calls

[Ab Abych]

Hello.

Now i am testind a 3CX station with AAstra 6753i IP phones (unfortunately, our organization have a lot of this devices).
All worked perfectly until yesterday. Yesterday, Aastra phones stops ringing - all outgoing calls (to 3CX Windows softphones) work fine, but Aastra phones don't accept incoming calls. In the log i see something like this:

Spoiler: LOG

18.02.2020 12:28:44:941 | 10 | [CM503003]: Call(C:40): Call to <sip:[email protected]:0> has failed; Cause: 503 Service Unavailable/INVITE from 192.168.202.180:5060
18.02.2020 12:28:44:941 | 10 | Call to T:Extn:0002@[Dev:sip:[email protected]:5060] from L:40.1[Extn:0004] failed, cause: Cause: 503 Service Unavailable/INVITE from 192.168.202.180:5060
18.02.2020 12:28:51:909 | 10 | [CM503003]: Call(C:41): Call to <sip:[email protected]:0> has failed; Cause: 503 Service Unavailable/INVITE from 192.168.202.180:5060

Spoiler: legend

0002 - phone extension for Aastra phone
192.168.202.180 - IP for Aastra phone
pbxtest.hostname.com - 3CX station hostname

Most terrible thing, that roll-backing to known good PBX configuration do nothing - phones Aastra still doesn't ringing.
I need to resolve this issue for understanding - can we use this Aastra phones in product with 3CX station or can't.

 

[Ab Abych]

Yes, and resetting phones Aastra to factory defaults has no effect.

 

[Ab Abych]

Solution found by creating custom template for Aastra phones. Settings was copied from old working configuration.