VOIP phones not reaching server across router

Posted on 2011-10-27
Last Modified: 2012-05-12
We have a Cisco 2811 and are separating our server/user traffic by putting the users on a separate LAN.  Currently all devices are in the subnet.  After the split it will be:

F0/0 - - This is the server subnet
F0/1 - - This is the user subnet

The office just installed a new voip phone system a couple weeks ago.  Since there were not two RJ45 jacks installed in all the offices/cubicles the network cable runs to the phone and then from the phone to the PC and they share an IP address.  This has been working fine on the single subnet setup.

We have configured F0/1 and took a user and gave them a static IP on the subnet for testing.  The PC works fine and they are able to get around the network and reach across the corporate WAN successfully.  However the phone doesn't work.  It states 'no system found' which we are guessing means it can't connect to the phone server that is on the subnet.

I have added the 'ip helper-address' command to the interface so we can get DHCP working in the new subnet but that isn't giving the phones a connection.
Question by:qbakies
    LVL 15

    Expert Comment

    What Voip phone system is it?
    LVL 10

    Accepted Solution

    I created an ACL (101) for UDP on port 50000 to the phone server in the 100.0/24 subnet and used the 'ip directed-broadcast 101'  statement in the f0/1 interface.  The phones are now able to connect to the server and make/receive calls.

    I'm not sure what system it is (this is at a remote location) and the support tech for the phone system insisted that we shouldn't have to do anything special for them to work.  When I told him that the ip directed-broadcast statement seemed to fix the issue he stated that the phones didn't use broadcast and we shouldn't need to do that.  Gotta love level 1 support.
    LVL 10

    Author Closing Comment

    Fixed the issue as stated.

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