Just follow these steps, and your calls will be forwarded from your landline to your cell phone: 1  Dial star-seven-two (*72) from your landline phone, and wait for a dial tone [source: ATT]. 2  Press the 10-digit number of the cell phone where you'd like your calls to be forwarded to [source: Vonage]. Press the pound button (#) or wait for a response indicating that call forwarding has been activated [source: Vonage, ATT]. Repeat steps 1 through 3 if you're not sure if the process worked [source: ATT].