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  • Data Modems

    Has anyone deployed modems for making a data call through the system out a PRI? Common place in the Nortel/Avaya world, didn't know if that was in any way problematic in the ShoreTel world. Scenario is if a data circuit goes down, the router uses dial back-up and uses the PRI on the Shoretel system to route the call. Any reason that shouldn't work??

  • #2
    A modem is an analog extension, like a fax...thats no problem, but you are saying if the WAN goes down, you would like to use dial up? I dont think thats a good idea. Have you looked at PSTN failover? This situation is what PSTN failover is for.


    • #3
      Nope, there is no reason why it shouldn't work. But I can tell you that ShoreTel does have issues with modems/faxes calling out analog and PRI circuits. I have been fighting this modem and fax issue since version 9.1 and I my theory is that its the DSPs in the SG switches. I think the push to T.38 has created issues with modems and faxing, which is a dirty connection and that creates 10% failure rates in faxes and modem calls. I believe changes were made in the DSPs to accommodate T.38, which left a void on the modem and fax side.
      Just my two cents, but yes it should work just as well as the other telcom manufactures (Avaya, Mitel, etc.)


      • #4
        I have this scenario in a number of spots and have not trouble with it for the most part. The portion of the equation that seems to change when I do have problems is the carrier. I have gotten a number of excuses from them as to why this is not their problem but most of them I can test and prove to not be true, I personally think some of the carriers have trouble doing conversions for FAX and keeping it from getting messed up...but that is just my two cents, it is also highly likely that it is a combination of factors when there are issues. But for the most part my experience has been that they just work if you identify them as fax extensions and make your fax codec g711.


        • #5
          just as a clarification.....I'm talking about a dial back-up scenario for their data network. So if their frame-relay between X and Y goes down they can have a modem set on one router to dial a modem at the other location, using the ShoreTel system's PRI as the outbound trunk path. Nothing to do with faxing or voice at all. Everyone still have the same opinion that it should be fine?


          • #6
            Dial Backup

            Network Dial Backup connectivity THROUGH a PRI.

            Never quite thought of that one.

            While it *should* work, i doubt that it would actually be enough bandwidth to be of any real use. I imagine there will be quite a bit of loss due to the double PRI conversion,etc. I would expect you will see about 14.4 of real throughput.

            Let us know how/if it works. It is an interesting idea.


            • #7
              I agree with eazeaz - I don't technically see a problem with the setup, but the practicality of actually being able to do anything over that dial up connection is slim to none.

              While it's not necessarily nearly as reliable as a frame relay connection, what about a cheap 1 or 2 meg cable or dsl connection as a backup instead with a site to site VPN to your headquarters? While you would have a monthly expense as compared to the free dialup solution, you'd be able to have it be at least somewhat functional (or even as functional depending on how much bandwidth you have with your frame relay connection).


              • #8
                Adtran Atlas

                The way I would do it is use an Adtran Atlas to actually terminate the PRI from the carrier and slice a BRI off of that to provide dial backup to the data network and then provide a PRI to the ShoreTel system. A little more expensive but I think you'll like the results better.

                Keeps the modems off the system and allows you to get reasonable backup data throughput.
                Last edited by Contractor; 07-13-2010, 08:12 PM.