Depending on which modem you have, equipment may have to be shipped to you. I suggest calling Customer Care at 855-463-9333. They can add the Voice phone service to your account, and determine if we need to ship the equipment, or if your modem has a phone port.
When you call into Care, make sure to ask about the number porting. The answer is most likely yes it can be, but there's a chance we can't.