Which prepay network for which country
 

Awefullly quite in here. How about a discussion on which prepay network to use where. As someone who has spent a week or so in quite a few countries I've found that getting a local prepay sim and slotting it into my tri-band gsm phone saves me a lot of cash. Usually need to make or receive only a few minutes of calls to make back the cost of the sim.

In the US I went with T-mobile as once you have added $100 of credit then any credit you buy (including the credit that took you over $100) will last for a year. I'm usually through the states once a year so this means I can keep the sim card :). I saw lots of ebay lots for sims (some were replacement sims not prepay ready sims) but bought from a T-Mobile store in the end.

In Buenos Aires, Argentina, I walked into a CTI mobile store and bought a prepay sim for 10 pesos (3 bucks) but it won't do international text messages :( ... I hear the Personal network might do?