I’m not sure if it’s common knowledge, but thought I would share.

I’ve had a good experience with the latest GPS tracker I’ve tried (some crap out of China that I can’t even put a name to, but with good features)

The important thing for me is that it communicates in part by calling you back. It will give me a ring after I give it a ring to let me know it has activated. This means that I can pick up and it will stop the SIM card expiring.

The SIM I’m using is from Meteor, and meteor has a top-up app; I can check the credit on the tracker and top it up very easily.

The combination of the call back and the top-up app meant I could permanently wire the tracker into the bike.

My bike is parked on the street; I can hear the alarm no problem, but if I’m out of earshot the tracker will send me an SMS when the bike is touched.

Secondly the V2 alarm recommended on here is great, and so loud it triggers the tracker’s shock sensor which sends me an SMS.