All GSM networks use the same roaming system. Prices are only comparable in the local market but the % upchange for roaming is roughly the same (eg roaming in India costs less because they only charge a small amount of rupees to start with). That said, prices for roaming can vary. In europe it's mostly the same or less than us (they travel cross boarder more than us naturally).
The only major countries with issues are China, some US networks and Japan who use different network types. By and large the home networks use this as a stick to charge the users more.
The only major countries with issues are China, some US networks and Japan who use different network types. By and large the home networks use this as a stick to charge the users more.