Traveling (with) 3G HSDPA GPRS - don't roam - get prepaid

I recently learned the tough lessons of roaming, whilst in Lisbon I received 6 calls which I screened and sent to voicemail. That cost me R450 (more than my average monthly bill for 220 minutes). I also learned that if you roam on your data connection (something that I would do), it will cost 20-100 times your usual cost. Ridiculous!

The way to beat this is have someone look after your phone at home. If you want to pay the international rate of forwarding, then get that person to set up a manual forward to your prepaid number that you get when you arrive in country of destination. (seasoned travelers have multiple SIMs - what's the best SIM pouch?)

So buying a local prepaid SIM is the way to go. Useful site - http://www.prepaidgsm.net/ - has info worth perusing. They don't have info on SA which generally has a cost of R2/MB (or ~£0.15/MB). But it appears from a brief scan of the UK that the SIM to get is Threepay - offering 3G: £ 0.50 per 60 minutes (max 2MB) or £ 1.00 for 24 hours (up to 4MB). As opposed to the one not to get is Vodafone GPRS/3G: £7.50/MB - €11.03/MB