asterisk users - Oct 2004 - Re: Benjk's Question "Why FXS"

How about a school strapped for cash, with around 60 POTS phones on
hand and an almost free source of another 60? Versus a cost (here in
Austria) of $99 for the cheapest VoIP phone (the cheapest Grandstream
model). Of course that also means that FXS is only of interest if
I can get it for under around $50-60/port -- if things cost more it
becomes easier to argue early replacement of these POTS phones by IP phones.


Benjamin on Asterisk Mailing Lists <benjk.on.asterisk.ml@gmail.com>
writes,
>I don't really understand the obsession with FXS devices.
>
>The only uses I see for FXS are
>
>- connect a FAX machine, where FAX may not be the best application for
>VoIP anyway,
>- connect an existing cordless phone, where you probably have only one
>such device and a Grandstream HT286 will just do fine,
>- connect the analog phone in a hotel to a travel adapter, IAXy would
>seem to be the best choice here because you are so much more likely to
>encounter NAT traversal problems and other obstacles that you may not
>be able to resolve with a SIP device,
>- feed some Internet based phone services into a legacy PBX that wants
>to see them as CO lines, here again, depending on the number of feeds,
>HT286 may be cheap and cheerful enough.
>
>For anything else IP phones should be the default with no buts and no
>ifs. I am always puzzled by how people desperately hang on to legacy
>stuff they don't really need and in the process create a beast of a
>kludge technology. The x86 architecture (or lack thereof) should be an
>example that serves to show how not to design your stuff with legacy
>support as your all-overriding number one priority. So, let's not make
>the same mistake with VoIP. Let's get rid of analog phones as fast and
>forcefully as we possibly can.
>
>In other words, FXS should be the very very last resort when there is
>really no other way.
>

Wolf Paul wrote:
> How about a school strapped for cash, with around 60 POTS phones on
> hand and an almost free source of another 60? Versus a cost (here in
> Austria) of $99 for the cheapest VoIP phone (the cheapest Grandstream
> model). Of course that also means that FXS is only of interest if
> I can get it for under around $50-60/port -- if things cost more it
> becomes easier to argue early replacement of these POTS phones by IP 
> phones.
For that many analog phones, you probably want something like a channel 
bank(s), which can handle the both FXS and FXO lines and package them 
into T1's. These are pricey new, but if you have the flexibility - and 
many school financial officers frown on buying used or surplus equipment 
- you can get them on e-bay quite reasonably with a little effort. I was 
able to get my FXS/FXO cards (4 port) for about $25.00 (US) per analog 
line and a virtually new TSU-600 for $99.00.

Stephen R. Besch