In most cases your BlackBerry device automatically connects to the appropriate wireless network when you travel outside of your wireless service provider's coverage area. In some cases you must contact your provider to have your micro SIM card or device properly provisioned. If you're not sure if your device is set up for roaming, or what roaming fees will apply, it's a good idea to check with your wireless service provider before you travel.
Your BlackBerry device is designed to switch to an appropriate wireless network automatically when you travel, but you might need to try switching networks manually if you're having trouble connecting or if the network signal is weak.
To switch wireless networks manually, your wireless service plan must include this service and your device must be connected to a GSM or UMTS network.
Depending on your wireless service plan, you might be able to turn off data services (email messages, PIN messages, text messages with attachments, and browser service) on your BlackBerry device so that only the phone and basic text messaging are available.Turning off data services while roaming might prevent you from receiving additional roaming charges. For more information, contact your wireless service provider.