I was trying to make sure that I can do everything I need to with my United Mobile sim card when I go on vacation to Europe. I had previously used it with a Treo 650 with no problems, but it seems as if it is a little trickier to use it with the Centro.
I figured out how to get the callback system to work with SIM Services, but was having trouble sending SMS messages. Their support staff indicated that I may need to update the "SMS Service Center" number.

Anyone have any idea where this is on the Centro? I found something under Messaging -> Network -> Network Configuration: Manual ->Edit -> Message Center Number, but that did not seem to work. Is that where it is supposed to be?