Azimout's Linux weblog


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I have a Ubuntu machine that’s always on and has an internet connection. I also have a couple of old PCI PSTN modems lying around. I wanted to find out if it’s possible to connect a POTS modem to the PC, attach a phone to it, and then use the phone through the modem through the PC through the internet to make a phone call (probably using SIP).

However if you don’t know the correct terminology it’s difficult to find a how to. So after a bit of googling and reading, I found out that:

  • what the telephone company is providing to you through the phone plug in your wall is a Foreign Exchange Station (FXS).
  • if you connect a phone to the plug in the wall, your phone is a Foreign Exchange Office (FXO).

So now I know that I want to find out how to make a PC with a PSTN modem into an FXS.

Update 11.08.2010:

The dahdi-linux version included in Maverick (2.2.1) does not compile with Maverick’s kernel (2.6.35). The issue is solved in the latest upstream (2.3.0), now let’s hope they merge it.

Also, I found out that it’s not possible to use a softmodem as an FXS, as it isn’t built to provide power to the phone. The cheapest FXS card is 100-150€, so I’m giving up… 😦


Written by azimout

07/08/2010 at 17:14

Posted in Reference

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