When I got my Samsung Galaxy, I found I could receive text messages, but not receive them. Strangely, if I put my SIM card in my friends G1 I could send text messages, and if they put their SIM card in my Galaxy, then could send text messages. The issue is the version of the SIM card, the T-mobile firmware on phones works around it and hardcodes a value for T-mobile. The solution, is to get a new SIM card.