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  • 1.  POTs over LTE

    Posted 06-13-2022 02:13 PM
    Edited by Adam Schuyler 06-13-2022 06:17 PM
    Hello all! We've recently had some issues where Verizon is starting to discontinue POTS service to some of our locations and in researching alternatives we're being offered a POTS over LTE option. I'm just wondering if anyone has used these services and if so we're fax transmissions reliable over them? We typically do not support the facilities infrastructure so I'm not overly concerned about supporting elevators or other power sensitive applications, but I have historically not had good luck with Fax over SIP so not getting a warm fuzzy around the idea of POTS over a cellular data connection. Any feedback is appreciated!

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    Adam Schuyler
    Principal Telecom Engineer
    Science Applications International Corporation
    Orlando FL
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  • 2.  RE: POTs over LTE

    Posted 06-13-2022 02:49 PM
    Writing this from a perspective of the midwest region.  NE and SW region might be slight different. 

    Verizon's VoLTE home units that they are offering as replacements use a highly compressed codec similar to G.729a.   I would be surprised if faxing works across those connections, even if you have a clean signal and everything is good.  The VoLTE home units seem to be the ones that Verizon is shipping by default for most customers.  

    Verizon also has an 'enterprise' unit that is supposed to be configurable to allow high-bandwidth codecs.  In theory, if you can find the right engineer, those units can be configured to use a codec that should allow faxing.  I've been told that most of those units are back-ordered for several months (6+), and finding the right engineer who will actually configure them will be, well, fun.  I don't know if I would rely on this solution working for faxing, but it could work.  

    If you still need to support faxing, I would recommend looking at a facilities-based solution.  SIP over fiber would be the best -- even if the solution does not officially support faxing, it should be more reliable than VoLTE.  If you can get the provider to support T.38, that would be best, but I've found providers support G.711 and lock you at G.711, you should be able to support faxing fairly well.

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    Nick Kwiatkowski
    Director of Design and Engineering
    Michigan State University
    East Lansing MI
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    Original Message


  • 3.  RE: POTs over LTE

    Posted 06-13-2022 06:16 PM
    Thanks Nick, sounds like we are on the same page.

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    Adam Schuyler
    Principal Telecom Engineer
    Science Applications International Corporation
    Orlando FL
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    Original Message


  • 4.  RE: POTs over LTE

    Posted 06-15-2022 06:07 PM
    Adam, I know it doesn't answer your question, but if your industry allows it, it might be a good opportunity to look into a cloud fax solution. We use one from Concord Technologies and have been pretty happy. Telco mandates and facilities moves can be great opportunities to get rid of physical fax machines.
    Original Message