Set mine up with a 99p O2 PAYG sim from a corner shop. The device takes 'normal' size sim cards, however it comes with adapters from nano -> normal and mini -> normal. It also comes with a sim extraction tool - this is for your phone presumably, as the device uses a push to remove the card, having some tweezers to get it out help since it doesn't quite come out far enough unless you have nails. Once it's actually in it's very unlikely you'll be taking it back out anywayFor O2..Whilst charging the device via USB. Purchase and top-up an O2 sim card (£10 etc), the O2 website didn't work for me when paying by CC ( it kept saying an error occurred but not why ), however a top-up card from a shop ( my local petrol station in this case ) did just fine. Insert the sim card and just follow the step by step instructions in the surprisingly not-too-bad manual, response times between each setup text is roughly 4 - 5 seconds.For APN settings use APN : payandgo.o2.co.uk, User : payandgo and Password : password.For security I set the speed alert to be 20km/h since this is for a second car and used infrequently, if it's moving at that speed then, well, someones nicked it or I've left it rolling down a hill. I just have to remember to set the alert to some ridiculous speed that I can't attain before I set off.Shock alert supposedly lets you know when the vehicle starts moving, however this triggered for me once when the car started, and yet another time didn't trigger at all. So for me Speed alert is the safer option. There's no configuration options for shock sensitivity.By default the time of the alerts were an hour out due to Daylight Savings, however this is configurable. This works fine and takes just one text message to the tracker to re-configure.The app if you decide to use it is really quite usable, no frills - does the job, is free, hasn't crashed, realtime tracking works fine and uses google maps (on android at least). Accuracy is supposedly 5 meters. That's a touch off for me, car is at the rear of the house, tracker says its at the front and I don't live in a shoe box, but I can live with that.All in all, this is much better than I expected, easy to setup, solid as a brick - in fact very weighty, could happily knock someone out with it, the magnets are also VERY strong.Assuming it lasts would happily buy another. Any questions just shoutUPDATE ( after one month ) :The shock alert actually fires mostly okay, it's not what anyone would call consistent but whilst the truck was in for servicing I could tell when they were working on (or moving) it. It occasionally fires when I get in the truck and start/move it, sometimes not. It's very much dependent on where the tracker is located and perhaps the vehicle. I'm still not going to rely on it.The disparity I've mentioned between the tracker's location and where the truck actually is ( in my case was a healthy dose of meters ) was down to the location of the tracker in the vehicle. The truck has aluminium panels so I'd positioned the tracker down low, this was entirely my mistake as I'd wanted to use the magnets to ensure the tracker didn't move, moving the tracker up higher and the tracker is detected much much closer to where the truck is. The manual suggests 5 meters, it's actually now down to less than that thanks to just positioning it a touch higher.I've only had one oddity, the tracker sent me a text to inform me the truck was at 0km/h (my speed alert was set to 20km/h), and it wasn't a shock alert, I'm not even sure what it was, perhaps a heartbeat, albeit after three weeks, however the manual that I have doesn't mention such a thing exists. Checking the vehicle showed it was fine. Out of the multitude of alerts I've put it through this was the only one that stood out as odd. It's only happened once.I should also mention that the app helpfully shows the current battery life, after four weeks mines at 40%, which so far, within reason, tallies with the manufacturer's expectancy considering I've mucked around with it within that time. They say 90 days, I reckon an easy 60 days no problem and 90days may be possible if I stop abusing it, plus charging it is fast, like, sit down have a meal and watch a movie fast.My Mum now wants one, not sure why, if anyone nicks her car then they're probably not going to get very far, but still, for the price if it gives her peace of mind then so far I'm happy to recommend it to her and anyone else.