global roaming - how long stays active

[adam917]

Originally Posted by Stu

Mobal uses the 02 network which is the gold standard in roaming, but you will be paying with "gold." If your first stop on your trip is the UK, I'd get a Vodafone SIM. You'll get free incoming throughout Western Europe this summer and all calls to the UK from a Voda affiliate will be local calls. (Your phone will default to Vodafone's European network). I'd get a cheap US calling card with European dial-in numbers and use it. You'll probably be able to keep your SIM swapping to a minimum.

What is so special about O2's roaming agreements that makes it the 'gold standard' when compared to other operators' roaming agreements? What about Vodafone or other multi-nationals like Orange or just large operators like China Mobile, AT&T, and Rogers Wireless?