[andrewpi]

I haven't heard of a 'do not port' instruction, but you can call T-Mobile and add an additional password that will be required before customer service will service your account.

[pxeboot]

Unfortunately numbers can usually be ported out with just name, account number and zip code. There is a lot of port fraud happening.

[exhilaration]

I ported my wife's number last week from Verizon to Sprint, a 4 digit PIN was required in addition to the account number and phone number.