I'm fairly certain I already know the answer, but I'd appreciate it if someone can confirm this for me.

I have a UK T-Mobile G1 on contract. I intend to purchase an unlocked and sim free Motorola Milestone. Am I correct in thinking that I should be able to just transfer the SIM from the G1 to the Milestone and have it function correctly on my current contract?

Thanks in advance for any help you can provide!