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3CX Dropping calls

Discussion in '3CX Phone System - General' started by joshuab, Feb 10, 2016.

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  1. joshuab

    Feb 2, 2016
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    Hi guys,

    Setting up a client with 3CX and got a SIP Trunk with a local provider. When they make any calls they will drop after about 30 seconds.

    Our SIP Trunk provider stated:
    "Upon reviewing the SIP signaling logs for your provided call sample, we can see that your 3CXPhoneSystem sent responses from port 57454, but in the '200 OK' SIP message, we received port 5060 in the contact header so our system sent ACK messages to that port. The 3CXPhoneSystem should send an appropriate port in the contact header."

    So why is 3CX sending messages back to our SIP Trunk provider to use a different port?

    - Have SonicWall Router
    - Disabled SIP ALG
    - NAT'd all necessary ports for 3CX
  2. NickD_3CX

    NickD_3CX Support Team
    Staff Member 3CX Support

    Jun 2, 2014
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    In order for 3CX to work behind a SonicWall, you must either have a One-to-One NAT or if you want a Many-to-One NAT you must have the necessary HotFix as outlined in the following document:

    In the case of Many-to-One NAT, in the above document you MUST see the "Disable Source Port Remap" as shown in step 4a otherwise it will not work.
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