3CX & BroadVox do not handle RFC 2833 DTMF Correctly

Discussion in '3CX Phone System - General' started by robhicks, Mar 10, 2008.

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  1. robhicks

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    Here's my ongoing saga.

    I'm testing 3CX to see if we want to buy it. We're using a SIP trunk from BroadVox. Most things are working now. However, frequently callers (most of them) calling into our PBX from BroadVox are getting misrouted. They receive an IVR when connecting. The IVR lets them dial an extension, which our case is a 3 digit number. In most cases, the PBX drops or doesn't get the initial 1, so they either get an invalid extension, or for some strange reason, the PBX forwards them to extension 111.

    I turned logging up to debug. This is a typical call into the PBX that is sent to extension 111, even though extension 115 was keyed in.

    From what I've read on this forum and Voxilla, it appears this is a DTMF issue. I've asked BroadVox which says they comply with RFC 2833 for DTMF so it is 3CX' problem. I assume that 3CX is going to tell me the same thing based upon previous posts.

    All of the internal extension phones (GrandStream GXP 2000) are using RFC 2833 (via RTP (RFC2833) ).

    I would appreciate any help. If 3CX and/or BroadVox cannot handle this kind of scenario, can someone point me to a PBX/provider that can?

    Rob Hicks
     
  2. robhicks

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    More on this. I just finished a testing session with Broadvox. Apparently, the first digit that is depressed after the phone call connects is being dropped. They don't know why but suspect it is either a delay in their system or in 3CX.

    Has anyone else seen this?
     
  3. LORD ORION

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    The best way to check is to use wireshark to see if the DTMF event is seen in the RTP.

    Just look at "VOIP calls" in wireshark and "graph it". You should see the RFC2833 DTMF events to see if they are what you expect.
     
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