low-density PSTN gateway (was Re: [Serusers] Firewall and NAT

Greg Fausak greg at august.net
Thu Jul 24 17:04:33 CEST 2003

FXO is Foreign Exchange Office, or the telephone company.
FXS is Foreign Exchange (Something?), the actual telephone device.
If you want to plug in a phone, you must use FXS.
If you want to create a PSTN gateway, you must use FXO.

We have experimented with several FXO cisco devices.
None are too expensive.  The Cisco 17xx series is a good
device that accepts VWICS that can be FXO or FXS.
The Cisco 26xx or 36xx with a NM-HDV (?) card accepts
VWICS.  I've used the POTS based VWICS and the ISDN based
ones.  ISDN is better.


> -----Original Message-----
> From: serusers-bounces at lists.iptel.org 
> [mailto:serusers-bounces at lists.iptel.org] On Behalf Of Jiri Kuthan
> Sent: Thursday, July 24, 2003 1:17 AM
> To: Rich Adamson; serusers at lists.iptel.org
> Subject: low-density PSTN gateway (was Re: [Serusers] Firewall and NAT
> At 02:23 PM 7/23/2003, Rich Adamson wrote:
> >Think the FXS is a Foreign Exchange interface intended to tie
> >a ser-accessible gateway to a telephone/pbx line (not to a
> >telephone instrument).
> I always thought that was FXO but I periodically confuse these
> two abbreviations. Anyway, if folks want to have a low-cost 
> analog-line gateway, the cheapest I'm aware of are ~1000+ with
> four analog ports. That's audiocodes and allied telesyn -- I never
> tested them though and my hand-waving guess is that these 
> products still need to mature.
> If anyone is aware of an affordable PSTN gateway, let me know.
> -jiri 
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