Are 3rd party purchased phones covered under PHP?

Hello guys, I originally got a Mytouch 4G through t-mobile about a year and a half ago, with PHP on our account from the get-go.

However I recently just purchased my friends extra T989 T-Mobile Galaxy S2 that I'm going to replace my mytouch with and use as my main cell. I'd like to know if the PHP insurance rolls over onto this new phone, if it can be purchased extra, and what do I need to do to enroll this new phone into the PHP and onto my account?

Or is it as simple as just putting your sim card into the new phone? (which I did and am using now)

Anything I need to know basically!

Thanks.