I have 6 lines but 5 iphones still needs to be paid off under tradein , so if I switch then will lose trade in value
Kind of. I'm in a similar position, but with 8 lines, and 3 phones still have over $1000 left on installments, but they're getting credits. Switching would mean we have to pay them off. T-Mobile does appear to offer some kind of credit for these situations, but I believe it's up to $650 per line. Depending on everyone's specific situation, it might make sense to go for it, or wait a little and switch later, or not switch at all. Right now, our coverage with AT&T is good, I will need to test T-Mobile first, and some of my family members are in different states, and we will need to make sure it works for them too. I'm not worrying about it right now, but eventually, I'll be checking my options. Google Fi looks interesting too, and I hear Mint Mobile is pretty popular.