Buying a phone on a tab is a little different though because the service provider has the right to label a phone that's still on a tab as stolen if it's used on a different carrier before the device balance is fully paid off resulting in the phone being blacklisted nationwide across all carriers. I had this happen to me when I purchased a phone back in 2018 that got blacklisted 6 months later for exactly this. I didn't know about this until I asked the seller after my phone got blacklisted. In the OP's case, they're trying to give it to a friend to use with a different carrier which is slightly different from my situation but the consequences could still be the same since the phone's device balance wouldn't have been fully paid off yet.