What APN were you using..? Was this from an iphone 3g,3gs,4,4s..? If im correct when you get an iphone 4s the account is provisioned for hspa+. I am using a sim from an iphone 4 and have yet to receive a message. So it seems strange.. ive had my tab for a few weeks already...
Sent from another Galaxy...
Nexus 4 | 16GB | PA 2.99
Nexus 7 | 32GB | WiFi+3G (Unlocked) | PA 2.99
Nexus 10 | 32GB | WiFi | PA 2.99
Galaxy Tab 7.7 | 16GB | WiFi+3G (Unlocked) | Stock TouchWiz ICS 4.0
HP TouchPad 4G | 32GB | WiFi+3G (Unlocked) | Stock WebOS