I purchased this sim to check my phones compatibility, now I'm looking to switch to the "one" unlimited plan. However I see no option on my account, is it possible or do I have to purchase a separate sim card?
Best answer by e2k
You have to create a new T-Mobile account. They will give you a temporary number. Then you have your prepaid number ported to your new postpaid (T-Mobile One) service. I suggest doing so during the last week of your billing cycle, as you prepaid balance will not carry over to your postpaid service, and there is no proration.