New phone

I have been with Comcast Mobile for several years,  2019 i think. I bought my phone from them,  Samsung Android. 

I paid off in couple months. 

I'm in need of a new phone. 

Do I need to buy from them, (which I had to in the beginning, since that didn't contract with Samsung then for currently owned phones) or can I buy a new one,  Android have it connected?