Unlocking an AT&T phone to use for Verizon

Please help. My father passed away over a year ago and when he died At&T told us we could keep his phone which is an iPhone 7Plus. We paid the remaining service bill and I wanted to pay off the rest of the phone (about $200 left) but they said that was forgiven. I let the phone sit for over a year because I wasn't ready to use it. His death was very difficult for me.

When I went to use it, I took it to a Verizon corporate store and they said I needed to contact AT&T to unlock it. I went to AT&T and found out that the phone was in collections because someone didn't file the death certificate correctly. After  probably 20+ hours on the phone and in person with AT&T, we got the phone out of collections at least BUT they will not unlock it because I am not an AT&T customer and they do not want me using it for Verizon.

How nice is that ? AT&T will give me the phone but I can't use it?

Has anyone else encountered this problem ?

I am considering opening a non-contract AT&T account to get them to unlock the phone and then cancelling it after one month.  However I want to be sure I can then take my SIM card from my old phone and it will work. The guy at Verizon said I can also just turn in the phone and get credit towards a new one at Verizon. I don't really want to do that as it was my dads phone. Everytime I pick it up it reminds me of him.

Any and all advice is appreciated !

Thanks !

Re: Unlocking an AT&T phone to use for Verizon

Did you figure out how to unlock it? I need to do the same