Users who want to get service with Straight Talk but already have a compatible device are able to simply purchase a SIM card through Straight Talk and get a new number without buying a phone. Users who have compatible phones also have the option to keep their existing phone numbers and still sign up with Straight Talk. As of 2015, no activation fee applies for either option.
Getting a number for an existing device requires that the device is compatible with the AT&T or T-Mobile GSM networks, or the phones have to be unlocked and be able to work with the 850 MHz and 1900 MHz GSM bands. Users can check availability and purchase SIM cards on Straight Talk's website.