I have iPhone 8 plus bought outright from best buy. I used another company sim card in the USA after purchasing the phone. Now I moved to Canada an trying to use my phone with Canada's network but it shows the phone is locked under carrier activation policy. How do I unlock my phone? I already called T-Mobile 2-3 times but didn't receive any response. Please advise.
Welcome to Apple's reseller flex policy that let's 3rd party companies sell their phones
as unlocked but then locks them to the first carrier once a sim is inserted. It's a stupid policy but it's Apple's.
Your best bet is to reach out on Tmobile's Facebook or Twitter pages using messenger to see if they can fix this for you.
Since Tmobile didn't sell the phone they won't have it in their sales data base so it has to
be added so they can request the unlock from Apple.
Manage your T-Mobile account