I've thought about getting a Pyra and then trying to use it for regular phone calls as well. What's not clear to me is what the landscape is for telephone software running on Linux that directly accesses the sim card. Does anyone know? I recall there being a libgsm, but a quick search isn't pulling up much information. I also recall there being at least two Raspberry Pi phone projects, this being one of them:

https://learn.adafruit.com/piphone-a-raspberry-pi-based-cell...

The software for this project can be found on github:

https://github.com/climberhunt/PiPhone

Candidly, the code there looks pretty simple. Most of it is using pygame for the graphics and then just sending serial commands to the modem. It looks like most of the complicated functionality is just part of the chip.

Anyway, yes, I've thought about doing a phone implementation on top of some kind of Linux distribution and Pyra was high on that list. If someone else has some information or knows of other projects that have done this, please let us know.