Careful with the patents... Cellular technology is an IP minefield. However, as long as you stay small and do it for educational value and fun -- you're OK. A

Careful with the patents... Cellular technology is an IP minefield. However, as long as you stay small and do it for educational value and fun -- you're OK. Also -- there's a big difference between making a call and sustaining the call across handovers, dealing with base stations from different manufacturers, etc...