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  • Remote IP phone, connects but can't place calls (inter or extra site)

    I have a dual site installation with about 500 phones. I also maintain a couple of datacenters, and I desire to put a phone in each, and let it access HQ site via our private WAN. The phone therefore, does not share the same subnet with the switches/server, but it does boot, grab the correct bin and show as available. The display service seems to work fine, it will let me browse the company directory, etc without issue. For sake of argument, the phone which is in the datacenter has extension 9793, and a phone local to the HQ subnet has the extension 9595.

    Whenever 9793 tries to dial 9595, the phone show's "959" but will not show the last 5. No ring audio ensues, nothing happens. The same thing is true when dialing a public number from 9793, all the numbers are entered accept the last one.

    Whenever trying to dial from 9595 to 9793, it takes about 6 seconds and then then the backup autoattendant comes on, saying that 9793 is currently unavailable.

    I was able to capture traffic at the packet level and noticed an interesting anomaly. The local 120port switch sends out 2 duplicate MGCP CRCX packets. The remote phone (9793) responds '200 OK' but only one response. The switch doesn't seem to recognize the response, because it continues to send the exact same requests in duplicate every time. Same connection id's etc. After a number of these repetitions, the switch sends DLCX and stops trying.

    All of these packet captures are pulled directly from a monitor port on a layer2 switch after all the firewalling and routing has been done. I have verified that traffic moves from an IP layer freely between the two devices, all firewalling from the 9793 phone into and out of the network is wide open on all ports/protocols. Tracing from the phone's IP (from a test machine, with the phone off the net) works to all of the different shoretel switches.

    I'm at a loss, perhaps my configuration isn't supported, but I can't see why this wouldn't work. I'm going to try and set up a similar test without using the WAN to see if i can reproduce the issue.

    If anyone has any thoughts or as set something like this up, please let me know, I'm all ears.


    Justin Sharp
    Network Engineer - Team Lead
    Data Center Operations
    AdvancedMD Software
    T: 801.984.9595
    F: 801.984.9501
    [email protected]
    Unify your office’s practice management, patient engagement, and EHR needs with a comprehensive, scalable solution. See how AdvancedMD can make life simpler.

  • #2
    I would make sure you have the configuration correct for the site (server room), Ip address map setup for the site (server room), and that the user is configured to use the correct trunk group to place calls.


    • #3

      I'm about to show my ignorance. Is it required to set up a site for each seperate IP subnet? Even though there will not be a shoretel server or any switches (just phones) at that site?



      • #4

        I am thinking - u mentioned that when u dialed 4 digits extension and the phone only displayed 3 digits and then time out.
        Did you set you dial plan to 4 digits, i believed by default it is 3?