csp Yeah T-Mobile doesn't check IMEI, which is why I'm curious whether you tried US Mobile Verizon or T-Mobile based.
Verizon based = black sim kit
T-Mobile based= white sim kit
When you use the T-Mobile based one, they don't ask for IMEI (Just like T-Mobile), but the Verizon one does (Does anyone know whether or not Verizon checks IMEI? I know my friend is able to just move his sim between phones with no repercussions). Metro, which is T-Mobile, does check SIM, and only recently stopped charging $15 to move your SIM card.
Maybe it has nothing to do with the tower it's based on, just what the carrier decides?