For me it was this easy, 10 minute call:Install the T-Mobile App, Log in Create a T-Mobile ID: Choose “ACCOUNT” at the bottom of the screen If you have more than one number, only one of the numbers may have the T-Mobile ID option Click “T-Mobile ID”, wait for it to initialize Choose “Phone Numbers” and click “Next” under “LINK NEW NUMBER”. Then enter the number you want to change to Primary. You will get a text confirmation when the new number is linked. Once this is done, dial 611 and get a customer support rep. Explain you want to change primary account holder, provide the PIN on the account. Tell them your number is linked to the ID (they will check this anyway). They will make the change for you.
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