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Codec And Extension Problems

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I have the following situation which may require an offer from your side:

1) 2 different voip lines from 2 different Voip providers.
2) line 1 requires (provider specification) to use G729 codec and is used JUST to receive calls. Line 2 can use any codec and is used both to receive and call out.
3) a modem going to a router and 2 different windows server computers connected ( and
4) a sip pbx (PCBest Sip PBX v3) installed into computer.
5) a softphone installed into same computer (as extension) attending just line 2.
6) VoiceGuide IVR installed into computer, attending just line 1. VoiceGuide uses Dialogic HMP drivers which support G729. It works perfectly when line 1 goes directly to it (without passing through the PBX).
7) a dial plan in the PBX directing incoming calls from line 2 to local softphone on (as extension) and incoming calls from line 1 (using G729) to the VoiceGuide machine, on PC, as extension too.
8) of course all the above voip line configured as sip accounts in the PBX.
9) the router is programmed to forward ports 5060-65, 2000-8000, 10000-30000 directly to (the computer where PBX is running)... the so called virtual server setting.

(Note: when Voiceguide was configured as directly connected to line 1, without PBX, the above ports where forwarded to, the VoiceGuide PC internal IP).

My situation is as follows:

1) All SIP accounts can register without problems in the PBX.
2) all extensions can reigister without problems (appear as UP- idle). The VoiceGuide extension,, goes UP and offline alone with certain frequency (seem a sort of cycle), dunno why.
3) when I receive a call on line 2, the call is perfectly directed by the PBX to my softphone (zoiper) extension and attended without problems. Also when I call out using line 2 from softphone everything works fine.
4) when I receive a call using line 1, the call appears in PBX log/monitor. It appears incoming into VoiceGuide line monitor at, then VoiceGuide starts to answer but the caller can not ear anything and the call is quickly dropped (Voiceguide continues to send its message for a while).

The problems are then 2, all related to line 1 (which uses G729 codec) and the IVR software.
1) the fact that Voiceguide goes UP and Offline in a cycle when connected as extension to the PBX.
2) most importat, the fact that when passing through the PBX, it is not possible to ear the VoiceGuide message and the line is quickly dropped.

I am not sure of what is happening, but I think that a possibility regarding problem 2 is that the PBX is not using G729 codec. I do not know if it is necessary that the PBX also has G729 enabled in this case, or it would be sufficient that VoiceGuide has G729 enabled (as is with Dialogic Drivers).

About problem 1, VoiceGuide as extension going up and offline into the PBX, I have no idea of what may be the reason and what kind of setting should I change ... any suggestion is welcome.

Thanks for help

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It works perfectly when line 1 goes directly to it [VoiceGuide] (without passing through the PBX).


So looks like issue only arises when the call goes through the PBX.


Would suggest running WireShark on both systems. This will let you see what is happening with the SIP and RTP communication.



To limit WireShark capture to just SIP and RTP please specify this in the Wireshark's 'Filter' text box:


sip || rtp


The WireShark packet capture will show when the various lines where registered, how the calls arrived in the system and what RTP was sent during connection.


Use File->Export Specified Packets to save the displayed packets into a .pcpapng file.

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