Somewhere on my todo is "wire pager to cell phone", I think this would work by having a Asterisk system take the incoming call, send the (nationwide) page, pager is wired to phone, phone displays page as if it's an incoming call (while caller hears ringing), if callee decides to answer the GSM circuits get power and the phone calls the Asterisk box which patches the two together. If someone beats me to it, I'll buy one. Putting a RTL-SDR into the phone would take care of the pager circuit and make other neat things possible.