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  • Question for someone that knows SIP better than me!

    Hi all,

    We have a customer that uses the Ascom i75 as a SIP extension, on 9.1. They are having some pretty big problems, and I have been working with Ascom and the TAC for over 4 months on them.

    This is a factory, and there are a few people that walk around the entire complex constantly. So their i75 roams from Access Point to Access Point. When changing from one AP to the next, there is a few seconds that the i75 is not pingable. If they happen to have an incoming call during this time, or any other time that they are out of wireless range, the Shoretel switch drops that phones SIP registration. Although, the Ascom still thinks that it has a registration, so it doesnt request a new one until its expiration time. This means that once the phone does come back into range, the user has no idea that his phone is not working, but no calls can come in, and he cant make any calls.

    There was one guy that had a heart attack and couldnt call for help because his phone wasnt registered, and another time when an alarm was going off and the fire dept couldnt call the guy to ask if everything was OK.

    I can see in debugging on the SIP proxy switch that, when the phone tries to make a call, the switch gives it a 401 unauthorized, and doesnt allow the call to be placed.

    My question is this- is it a possibility for A) Shoretel to not delete the registration until the expiration time, or B) Ascom to try to register after getting a 401 unauthorized.

    I want to ask those questions to Shoretel and Ascom, but I dont know if its a stupid question or not.


  • #2
    Well, no those are not stupid questions, I guess mine in return would be as to what kind of WAP's they are running? We have a number of installs with Polycom wireless handset that are running on Trapeze wireless networks and the wireless controller handles the WAP to WAP hand-offs so that you cannot even hear the difference when it happens if you are on a call. All that to say I think the long-term solution might be to move them to a wireless solution that has an enterprise class controller that can handle the hand-offs so there is no connectivity drop in the first place. (Trapeze, Cisco, Aruba...)


    • #3
      It is absolutely necessary to have an enterprise class wireless network when running wifi sip devices.

      Another thing is there were some pretty well known SIP issues on 9.1. I had to lower the registration time dramatically on both the SIP cfg file for the phone and on the ShoreTel server so that the phone would register more often. Then I recently upgraded the customer to 10.1 and the SIP issues went away. I know it's a pain to upgrade but the SIP stack was completely redesigned and it solved my issues.


      • #4
        It is a Trapeze network. They are on 8.1, and the engineer that I've been working with said that 9.2 should fix this, so we'll be upgrading. Thanks guys!


        • #5
          If possible I would move to 10.1 there are even more SIP updates there and that should give you the best chance of clearing this up. Also I would ask whoever programmed the Trapeze controller how they have roaming set up. Moving from one AP to another should be seamless with the controller in there.