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No audio for calls from 3CX to DID external number

Discussion in '3CX Phone System - General' started by MichaelG, Dec 8, 2017.

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  1. MichaelG

    Nov 19, 2017
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    We are having a problem at the moment where calls from an internal extension to the eternal number of another extension have no audio. The call rings and connects, but neither end hears anything.
    User 1 (extension 5101, external DID 0299995101)
    User 2 (extension 5202, external DID 0299995202)
    If User 1 calls 5202 there is no issues. But if User 1 calls 0299995202 then the call connects but no audio.

    I would have thought that if 3CX gets an outgoing call for one of it's own DIDs then the call would have been automatically routed to the internal extension. Not sure if this is the case.
  2. sip.bg

    sip.bg Active Member

    Nov 7, 2016
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    This could be an issue with your provider, you are using the same trunk for outbound call to reach extension 5202 on its DID number.
    Try to capture traffic with Wireshark (tcpdump on Linux).
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  3. YiannisH_3CX

    YiannisH_3CX Support Team
    Staff Member 3CX Support

    May 10, 2016
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    the 3CX server will try and search for an extension number or a sip id. If there is no match then the call will be processed through the outbound rules as a normal call and will be routed to your provider.
  4. leejor

    leejor Well-Known Member

    Jan 22, 2008
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    As mentioned, calls would normally be routed out, using outbound rules, then back by your provider. There are a couple ways around this. You can assign the full number, as the SIP ID to the DID extension. When another extension dials it, the call will ignore the outbound rules, and ring that extension. Or...you can create a Loop trunk, which while still using two licences per call, will not have to route out to your provider.

    Back in 2011, Sy posted the "trick" (his words).

    "Re: internal users dialing did's instead of extension

    Postby SY » 25 May 2011 Wed 06:04:21,
    Technically, the trick can be implemented using loopback SIP trunk.
    1. create SIP trunk with
    2. create outbound rule(s) for this trunk. They should intecept all DID numbers
    3. attach existing inbound DIDs rules to this trunk

    If everything is done correctly then all outgoing calls addressed to DID numbers will go to the loop back trunk and then returned as incoming calls which will be routed by inbound DID rules."
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