Hi there! You have 150 days to resume service by paying your monthly payment in full or your account will be cancelled and you will lose all funds in your account balance and your phone number.
Is it really 150 days? These sources says 60 days:
Hi. Thanks for contacting us. Your account will cancel automatically in 120 days when you do not use the phone or add funds. When your account is canceled, you will lose your phone number and will be unable to port your number to another carrier.