# Asterisk and PSTN / FXO **URL:** \ **Category:** Asterisk Support\ **Created:** [February 17, 2006, 11:35pm UTC](https://community.asterisk.org/t/asterisk-and-pstn-fxo/4481 "2006-02-17T23:35:59Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![ilkera](https://avatars.discourse-cdn.com/v4/letter/i/9de053/32.png) [@ilkera](https://community.asterisk.org/u/ilkera)\ **Post date:** [February 17, 2006, 11:35pm UTC](https://community.asterisk.org/t/asterisk-and-pstn-fxo/4481/1 "2006-02-17T23:35:59Z")
Hi, I have a working Asterisk server with SIP trunks. Now I want to use my PSTN line also with it. I read everywhere that this configuration needs a special voice card named XP100. I know that it’s not too expensive but I have too many idle external modems at home. Is it possible to use external modems as FXO card ? I read different opinions on this issue but I couldn’t understand it well. If it’s not possible than I will go and buy a XP100 pci card. Please help me. Thanks ---
**Author:** ![meral82](https://sea1.discourse-cdn.com/asterisk/user_avatar/community.asterisk.org/meral82/32/1345_2.png) [@meral82](https://community.asterisk.org/u/meral82)\ **Post date:** [February 18, 2006, 12:00am UTC](https://community.asterisk.org/t/asterisk-and-pstn-fxo/4481/2 "2006-02-18T00:00:55Z")
it is possible but not simple. try equipment like lynksys pap2 (less then 80$, 2 fxo) ---
**Author:** ![p\_lindheimer](https://avatars.discourse-cdn.com/v4/letter/p/41988e/32.png) [@p\_lindheimer](https://community.asterisk.org/u/p_lindheimer)\ **Post date:** [February 18, 2006, 1:32am UTC](https://community.asterisk.org/t/asterisk-and-pstn-fxo/4481/3 "2006-02-18T01:32:37Z")
PAP-2 is 2xFXS not FXO. The XP100 card will do what you want and is probably the cheapest. If you want to go with an ATA, the Sipura SPA-3000 will do what you want (1xFXO, 1xFXS). p ---
**Author:** ![ilkera](https://avatars.discourse-cdn.com/v4/letter/i/9de053/32.png) [@ilkera](https://community.asterisk.org/u/ilkera)\ **Post date:** [February 18, 2006, 6:11am UTC](https://community.asterisk.org/t/asterisk-and-pstn-fxo/4481/4 "2006-02-18T06:11:50Z")
[quote=“p\_lindheimer”]PAP-2 is 2xFXS not FXO. The XP100 card will do what you want and is probably the cheapest. If you want to go with an ATA, the Sipura SPA-3000 will do what you want (1xFXO, 1xFXS). p[/quote] yes I know PAP2 and SPA 3000 but I don’t want to use a external VoIP equipment for PSTN calls. I am already using the PAP2 for connecting my DECT phone to Asterisk via SIP. (and it is FXS only not FXO) I just wonder if I can use my external 56K dialup/fax modems connected to the Asterisk server on serial port for this purpose. (dialing PSTN through Asterisk) If that is possible my idle modems will have a use 😄 ---
**Author:** ![IronHelix](https://avatars.discourse-cdn.com/v4/letter/i/da6949/32.png) [@IronHelix](https://community.asterisk.org/u/IronHelix)\ **Post date:** [February 18, 2006, 7:52am UTC](https://community.asterisk.org/t/asterisk-and-pstn-fxo/4481/5 "2006-02-18T07:52:12Z")
FWIW- FXS connects to a phone. (fxS Serves the dialtone). FXO connects to a Phone Line (telcO) that said, your old modems will not help. First, asterisk used to support a few soft modems but no longer does, mostly because few used it. Second, because you have the wrong modem. Serial cable modems do not have audio capability as a general rule. Even the internal ‘voice modems’ won’t work because many were real modems with sound card connections. What is needed is a ‘soft modem’, which is basically a sound card with a phone plug on the end (and a bit of extra circuitry for dealing with phone lines). This lets asterisk take full control over the line. Yoru cheapest option is a clone Digium X100p card, which was a rebadged Intel Tiger Jet modem. THe Wiki has a bunch of info for how to find the right kind of modem, or easier, buy an x100 clone from any one of several voip vendors. Hope that helps! ---
**Author:** ![ilkera](https://avatars.discourse-cdn.com/v4/letter/i/9de053/32.png) [@ilkera](https://community.asterisk.org/u/ilkera)\ **Post date:** [February 18, 2006, 12:19pm UTC](https://community.asterisk.org/t/asterisk-and-pstn-fxo/4481/6 "2006-02-18T12:19:13Z")
[quote=“IronHelix”]FWIW- Yoru cheapest option is a clone Digium X100p card, which was a rebadged Intel Tiger Jet modem. THe Wiki has a bunch of info for how to find the right kind of modem, or easier, buy an x100 clone from any one of several voip vendors. [/quote] Great information ! Thanks, it helps 😄 I will order a xp100 clone from ebay right now 😄 ---
**Author:** ![ilkera](https://avatars.discourse-cdn.com/v4/letter/i/9de053/32.png) [@ilkera](https://community.asterisk.org/u/ilkera)\ **Post date:** [February 18, 2006, 11:18pm UTC](https://community.asterisk.org/t/asterisk-and-pstn-fxo/4481/7 "2006-02-18T23:18:19Z")
My X100P clone card is on its way. I wonder now if I can run the card through an Asterisk installed on a Virtual host (VMware) is it possible to add the FXO card to my Virtual host in VMware ? ---
**Author:** ![dswartz](https://avatars.discourse-cdn.com/v4/letter/d/45deac/32.png) [@dswartz](https://community.asterisk.org/u/dswartz)\ **Post date:** [February 19, 2006, 2:39am UTC](https://community.asterisk.org/t/asterisk-and-pstn-fxo/4481/8 "2006-02-19T02:39:36Z")
I highly doubt it.