My thoughts are since MetroPCS is a prepaid/no contract carrier, that is what they have to say. It wouldn't make sense to open a new MetroPCS account if you are an existing customer. I looked at some other MetroPCS phones on Wirefly and they all say that - "with a new MetroPCS account".
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I'm thinking this as well. I have searched around the web and saw that people have ordered esteems in the past and already had accounts. I don't think this is an issue. I will wait till my order comes through and gets to my door.
EDIT: I have actually decided to cancel the order. I'd rather not have to end up losing my number or anything of the sort.