pi2gprs
USING INEXPENSIVE GPRS MODULES WITH THE PI ZERO
Wire as per pi2gprs.png in this project's files section.
Install the ppp daemon: apt-get install ppp
Download the fona file from this project's files page and copy it to /etc/ppp/providers. (Thanks Adafruit!).
Connect: pon fona
Disconnect: poff
Providers: hologram.io, freedompop.com, speedtalkmobile.com
More writeup to come...