If you're hacking around with phones or GSM boards for fun, on and off, it is cost effective to just grab one for a pound or so every time you want to do someth

If you're hacking around with phones or GSM boards for fun, on and off, it is cost effective to just grab one for a pound or so every time you want to do something as they sometimes come with a tiny bit of free data, or just a number to receive SMS on at least. If you don't top up (with say a tenner) within some months the card deactivates and becomes useless, so it's a no-commitment way to access the GSM network.