3COM NBX v3000:  No audio from remote phone to LAN but remote2remote works

Posted on 2006-04-26
Last Modified: 2010-04-12
I have setup remote phones to work with 3COM NBX v3000.  The remote phones are able to see the network, extensions, etc.

1.  From the remote phone, I can call any extension and any extension can call the remote phone.
2.  From the remote phone, audio from the other end can be heard. Whether it is other phones in the NBX network, or home phones and celllular phones, audio can be heard.
3.  PROBLEM:  No Audio (from the remote phone) can be heard on any phone OTHER THAN other remote phones.  Remote to Remote phone works perfectly.

NBX is running Software Version:  R5_0_10    

Any idea how to fix this?
Question by:top_rung
    LVL 2

    Expert Comment

    How do you have the remote phones conecting to the NBX? Do you have VPNs ?

    Do you have "IP on the Fly" enabled in the NBX? Do you have a range of IP addresses set up in the NBX?
    LVL 14

    Author Comment

    No VPN2VPN
    IP on the fly is enabled
    The NBX has a public IP then NATd to the internal LAN.
    The phones are behind a consumer grade broadband router using cable modem connections.

    The current release states that the remote phones support communication from behind a NATd device for use with cable modems, home connections. However, I just spoke to 3COM and they stated that they support it, but not NATd to NATd.  Deceptive if you ask me.

    They said the solution was to put the NBX on the public (not recommended) or use VPN routers at the remote connections.  They are almost there it sounds like, but not 100%.

    I am going to try the phone directly to the cable modem and see if it works.  If it works, do you know what the security implications are in having a phone open like that?


    LVL 2

    Expert Comment

    Remote phones support communication behind a NATd but only if the NBX has public IP and the range in IP on the fly is also public IP.
    It is confusing, and it hasn't been supported for very long. It helps in some situations, for example when having the phone behind internet sharing with a PC that established a VPN.

    Having a remote phone with a public IP should work since the phones inside your local LAN will know how to get to your remote phone.    I haven't tested it that way.

    Accepted Solution

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