Digium FXS specifications and limits Question

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Howdy All,

I’m considering Asterisk / Digium as a replacement to my existing phone
switch. I need to continue to be able to push analog lines between
multiple buildings in a campus environment.

The Digium Analog 410 Card manual states it’s not recommended to go
beyond 1500 feet distance for an FXS card, and no line should leave the
building or be bundled. The 2400 Series Manual does not have this same
notice. Should it?

My potential application will be pushing all of 1500 feet and maybe a
teeny bit more. Analog lines will be bundled into PE-89 type
direct-burial rated cable in capacities ranging from 100-pair to
500-pair. All cable pairs are 24AWG. All cable is privately owned by the
organization. All cable is professionally terminated on each end to
grounded building entrance protection with lightning blocks / surge
protection. This infrastructure has been in place and working on an
existing “old school” digital switch with port cards that don’t have
lightning or surge suppression built in, just like the Digium cards.

Has anyone run a similar configuration and can speak for or against such
an idear?

Thanks for the help and input,

Jason

6 thoughts on - Digium FXS specifications and limits Question

  • Yes. All of Digium’s FXS modules are designed for short-haul, inside
    wiring applications.

  • If you must do this, Mike Sandman (and probably others) has a line of
    loop extenders. I’ve used his stuff before to keep old POTS stuff
    running.

    http://www.sandman.com/longloop.html

    These devices may also give you a little more lightning protection than
    you already have, but I wouldn’t count on it.

  • Thanks for the info… The box looks very interesting. It looks like I’d
    still void a warranty if I used it though. 🙂 I’m OK with voiding
    warranties and pushing limits, but I wonder if anyone else has tried it an
    what the outcome was. I also wonder if there’s something out there from a
    different manufacturer that is designed spcifically to support my
    requirements.

    Thanks Again.

  • T1’s and channel banks in each building?
    The cost of a 24 port board vs a T1 and channel bank works out in favor
    of the channel bank
    Multiple Asterisk boxes?

    In the Telecom world, long line adapters exist to extend loops

    John Novack

    asterisk@ihearbanjos.com wrote:

  • This is the part where I say DUH!!! I don’t know why I wasn’t thinking
    of that. Thanks for the information and the brain jogging…

    Maybe I blocked it from my subconscious because I knew it would make the
    layout more complicated, complex, and costly than the current. I wish I
    could find something that would avoid the need to put more than just a
    network switch and an UPS in every building. As it stands now, in a
    number of buildings I’m only going to need two or three analog lines. I
    suppose I could go the ATA route, but I wanted to avoid the extra
    smattering of boxes I’ll have to maintain. I could keep my existing PBX
    and use it for analog ports only, but where’s the fun in that.

    Thanks Again,

    Jason

  • This is the part where I say DUH!!! I don’t know why I wasn’t thinking
    of that. Thanks for the information and the brain jogging…

    Maybe I blocked it from my subconscious because I knew it would make the
    layout more complicated, complex, and costly than the current. I wish I
    could find something that would avoid the need to put more than just a
    network switch and an UPS in every building. As it stands now, in a
    number of buildings I’m only going to need two or three analog lines. I
    suppose I could go the ATA route, but I wanted to avoid the extra
    smattering of boxes I’ll have to maintain. I could keep my existing PBX
    and use it for analog ports only, but where’s the fun in that.

    Thanks Again,

    Jason