Unfortunately I dont believe it's a file that can be extracted and copied to another device, but rather obtained through the *228 method.
From what I was told, you should use *228 when you're out of your home coverage area. Updating your phone while not within range of your home towers allows the phone to 'borrow' the signal from other towers in the area you're currently positioned in (typically, this will make the phone connect to a non-USCC tower and thus put your phone in roaming).
Roaming shouldn't be an issue if you're a USCC subscriber as roaming counts for standard minutes for majority of their smart phone plans and Belief program plans.
However, when I went to Tennessee last year, I couldn't even make the *228 call from my phone, but that could have been due to the abundance of extremely large trees in the area. City boy + country settings = technological frustrations (not to be confused with hemerrhoids).