Solved 3CX sending CANCEL to handsets - can't answer incoming calls

[ChrisHerrmann]

Hi all,

Just installed the 3CX Linux iso as a VM. I've got outbound & internal calls working OK, but having problems with inbound routes. When an inbound call occurs the phone rings for a fraction of a second then hangs up.

This occurs for the main trunk line, and all other DIDs that have been setup for ring groups, individual extensions etc.

If I test ringing a single extension that has no call forwards in place...

In the 3CX admin page I see:

07/13/2017 9:26:15 AM - [CM503003]: Call(C:5): Call to <sip:[email protected]:5060> has failed; Cause: 487 Request Terminated/INVITE from 192.168.30.110:2051

If I tcpdump on the phone and download the PCAP, I can see that the PBX itself is sending the cancel:

Session Initiation Protocol (CANCEL)
Request-Line: CANCEL sip:[email protected]:2057;line=xoq4bnoa SIP/2.0
Method: CANCEL
Request-URI: sip:[email protected]:2057;line=xoq4bnoa
Request-URI User Part: 402
Request-URI Host Part: 192.168.30.60
Request-URI Host Port: 2057
[Resent Packet: False]
Message Header
Via: SIP/2.0/UDP 192.168.30.11:5060;branch=z9hG4bK-524287-1---f2039d7c41957367;rport
Max-Forwards: 70
To: <sip:[email protected]>
From: <sip:[email protected]:5060;nf=e>;tag=34ad3a54
Call-ID: yNutAUDrMPjlFsLvgufmJw..
CSeq: 1 CANCEL
Sequence Number: 1
Method: CANCEL
User-Agent: 3CXPhoneSystem 15.5.1694.0 (1694)
Reason: SIP;cause=480;text="NO_ANSWER"
Reason protocols: SIP
Content-Length: 0

So this is a test from a mobile phone to a DID that goes directly to the extension in question, which shows up as being "green" in the admin console. The same behaviour appears for all inbound calls.

Any ideas where to start looking? Also is there any way to get realtime logs of what's going on or to test a call plan in the same way that you'd use the asterisk CLI? for example:

asterisk -r
show dialplan

etc etc?

Thanks,

Chris

 

[ChrisHerrmann]

The devices in use:
SNOM 320/360/370 with several firmware revisions
Bria Softphone
MicroSIP softphone

(these devices were all previously working fine with old Asterisk PBX).

 

[ChrisHerrmann]

OK worked it out. The problem was that there was a call forward setup by the provider on the main trunk number, so what was happening was:
- PBX is registered with provider
- Call comes in
- PBX finds extension in question, INVITES extension to join
- Extension starts ringing
- Provider sends CANCEL
- PBX in turn sends CANCEL to handset(s)
- Handset returns 487 Terminate

Worked it out by:
- Installing tcpdump on the pbx and watching what was happening on 5060

What would be reaaaaally nice is if the GUI actually told you what the provider had said - so you weren't guessing. Also the GUI should report on the message that it passes to the phones. Currently it's ambiguous and looks like maybe the phone terminated the connection, when it didn't.