Incoming calls ringing out without connection

Our setup is simple - Trixbox 2.2.3, Linksys 942/962 handsets, 60 extensions, pure VOIP incoming and outgoing (no PSTN or ISDN), ~400 incoming/outgoing calls daily.

We have a very annoying situation which happens only 3-4 times a day but is causing much grief. An incoming call will ring at the receptionist extension. As soon as the receptionist picks up it shows the call has ended. The caller however can still hear the phone ringing and it just continues to ring until it rings out. It does not go to voicemail as it should when the phone is not answered. If the caller hangs up and calls again sometimes he gets through, sometimes he gets a repeat of the same thing, if he persists he will get through eventually (max 2 tries reported). Some people just give up and don’t bother trying thinking the number is wrong <-- BAD. This has happened to other extensions with DIDs (which bypasses reception) too.

We have upgraded firmware on all phones (Linksys 942 to 5.2.5, 962 to 5.2.8SC) and tried different versions of trixbox (2.2.3, 2.4.0 and 2.6) tried some different extension settings in FreePBX (e.g. qualify=yes,no,200,2000 canreinvite=yes/no). We’re at our wit’s end, it seems like a simple problem but we have not been able to get any closer to a solution.

Any help is much appreciated.

A sample CDR of the problem is below:

Caller: 0425793xxx
Reception Extension and main DID: 201 SIP/039xxxxxxx

2008-05-12 09:14:23 0425793xxx 201 SIP/039xxxxxxx-09695f68
SIP/201-096fb9e8 ANSWERED 0 Not Recorded
2008-05-12 09:00:51 0398860xxx 216 SIP/201-096ecc78 SIP/216-09649b30 ANSWERED 825 Not Recorded
2008-05-12 09:14:39 0398860xxx 216 SIP/039xxxxxxx-096e7738 SIP/216-09649b30 ANSWERED 839 Not Recorded
2008-05-12 09:14:51 0386371xxx 0425793xxx SIP/201-097060e8 SIP/NexVoice-1-096fe700 ANSWERED 27 Not Recorded
2008-05-12 09:15:43 0425793xxx 201 SIP/039xxxxxxx-096e7738
SIP/201-09708a08 ANSWERED 0 Not Recorded
2008-05-12 09:16:25 220 *97 SIP/220-09701320 ANSWERED 38 Not Recorded
2008-05-12 09:17:37 0425793xxx 201 SIP/039xxxxxxx-09701320
SIP/201-09708a08 ANSWERED 2 Not Recorded
2008-05-12 09:18:48 0386371xxx 0424140xxx SIP/220-09708d08 SIP/NexVoice-1-097377b0 ANSWERED 133 Not Recorded
2008-05-12 09:21:21 0425793xxx 210 SIP/201-096e7738 SIP/210-09730738 ANSWERED 32 Not Recorded
2008-05-12 09:21:55 0425793xxx 210 SIP/039xxxxxxx-096efb98
SIP/210-09730738 ANSWERED 181 Not Recorded

we have 1 single DID trunk coming in and a 10 channel outgoing trunk.

the provided apparently requires the following entry in the extensions.conf file:


exten => _.,1,Noop(Fixing DID using information from SIP TO header)
exten => _.,n,Set(pseudodid=${SIP_HEADER(To)})
exten => _.,n,Set(pseudodid=${CUT(pseudodid,@,1)})
exten => _.,n,Set(pseudodid=${CUT(pseudodid,:,2)})
exten => _.,n,Goto(from-trunk,${pseudodid},1)

Outgoing 10 channel trunk:

PEER Details:


USER context:


Incoming single DID trunk:

Same settings as above.

The last entry that is required is in the sip.conf file. without this setting the trunks don’t register:


Some more background, We also had another recent issue with ghost calls from ext to ext and sometimes to themselves. we thought it might be hudserver and unistalled it. but then we found some forum posts relating to zaptel conf settings. Even though we no longer have a zaptel device installed, the drivers were still there so we removed them. now the paging doesn’t work! :frowning: but that’s not as important cos at least the ghost calling seems to have stopped! :slight_smile: