Asterisk on Raspberry Pi now has FXO, FXS and GSM Interfaces
The combination of Asterisk and Raspberry Pi harkens back to a time when I was seeking to run Asterisk on an small, embedded platform. I was a little ahead of the curve, seeking this before Digium released AsteriskNOW. I tried Michael Iedema’s Askozia PBX and settled upon Astlinux on a Soekris Net4801, which I used for a couple of years.
Of course, all this was before the now ubiquitous Raspberry Pi was released. It makes sense that someone would try that low-cost SBC as a host for Asterisk. However, there hasn’t been much hardware support for that effort until recently.

Today I read that SwitchPi is now offering modular and multi-port FXO/FXS interfaces, as well as a GSM interface.
- OAK8X base module (4 onboard Asterisk FXO channels) $130
- OAK8X base module with 8 channels (8 Asterisk channels, 4 FXO plus 4FXS) $180
- OAK8X base module with 8 channels (8 Asterisk channels, 8 FXO) $180
- PiGSM single channel GSM interface $99
- PiTDM base module $89
- PiTDM 2 channel FXO module $20
- PiTDM 1 channel FXS module $10
This is exactly the sort of hardware I tinkered with when I was using Asterisk. I used a TDP400P card with FXS and FXO interfaces. I also used a SIP-to-GSM gateway, documenting the project in the early days of this site.
SwitchPi seems have started in January 2018. It’s good to see hardware support for running Asterisk on Raspberry Pi evolving and affordable.