AT&T have released the new NumberSync service which lets consumers leave their phone at home and bring their number with them using the Samsung Gear S2, available for $99.99 with a Two-Year Agreement. With the service you are able to make and receive calls as well as the ability to send and receive text messages, all using your S2 that will have the same mobile number as your smartphone.
The new functionality is available for existing customers via a firmware / software update, but no additional steps required for new customers. You will need a Mobile Share Value plan (minimum $30 for a new plan or $10 to add to an existing plan) and the S2 for $99.99 with a two-year agreement.