help with 6620

[flipz]

anyone with great knowledge please help!!! i have a nokia 6620 and it is unlocked already...i inserted a smart sim card for philippines and the thing is, i can accept text and send text but only nationally... meaing only here in the U.S. i an't received text and send text outside U.S. now im thinking my problem is that my phone is not set up to 1800 frequency but i can't find anything on my phone that gives me that option of changing between bands.. so please anyone help me!!! thx

[Manoloff]

check your message center number. make sure it is inserted with a prefix "+" and the country code