I refilled my plan for one month at the end of June, but then I left the United States until September 1st. If I don't refill my plan in July and August, will my phone number be canceled, or can I use the original phone number again?
Yes, by then your same number will not be available for use when you return in September. If you'd like to keep the number, I recommend refilling your account (easily done online). Refill your prepaid account