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VOIP Firewalls

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  • #21242

    I am having a firewall issue with my new project.When I try to place phone calls to an extenal network,the firewall is blocking all UDP ports.Therefore,the calls do not go thru.Do anyone know a workaround for this?


    What equipment are you using?

    You need to find out what are the UDP ports used for signaling message communication between equipment. If you did, then configure the firewall equipment to allow those UDP ports to go through.. Hope this will help…


    You also have to look at the RTP port range of the devices.

    Here are general ports used:

    RTP stream 16384-32767 (UDP)

    For SIP:
    either UDP or TCP 5060 for the signaling

    A user agent MAY register with a local server on startup by sending a REGISTER request to the well-known “all SIP servers” multicast address “” (

    For H323

    Unicast GK Discovery 1718 UDP
    Multicast GK discovery (UDP)
    Registration/Status 1719 UDP
    H.225.0 (call signaling for hosts) 1720 TCP
    h245 is negotiated in the range of 11000 – 65535

    For MGCP:

    MGCP version 0.1
    MG and CA signalling – 2427 (UDP)

    MGCP version 1.0
    MG – 2427 (UDP)
    CA – 2727 (UDP)



    Do you know any good sites that I can research that on?


    I always just go to IETF to look up some of those things. Otherwise, I am really not sure where to go look anymore. I have been doing standards based VoIP since late 96′.


    I would avoid using firewalls in your design as they increase latency. Consider using access lists on your routers instead.


    ACLs work, but NAT and Firewalls are very big issues that need to be taken care of.
    One issue with ACLs is scale, how do you manage this once you have 80 partners with 10000 gateways each.

Viewing 7 posts - 1 through 7 (of 7 total)
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