If you still have an interest in telephony you might want to look at http://www....

If you still have an interest in telephony you might want to look at http://www.rowetel.com/blog/ and his work on the Mesh Potato http://www.villagetelco.org/about/mesh-potato/.

It's an open source hardware project to create an easily deployed developing world "village telephony" system.

Some really good content.