I'm currently in the process of using a GSM module for telemetry purposes in my latest project. I used the GSM900 from RF Solutions:
https://www.rfsolutions.co.uk/acatalog/GSM_Modules.html
The major downside to this module (from a hobbyist's perspective) is that it uses a very fine pitch connector so you can pretty much forget prototyping your own PCB with it. But if you're going to get your PCBs manufactured (and just hack onto it during test/dev period) then obviously it's fine.