T-Mobile announces that its T-Mobile Digits service will launch on May 31 and will be free. It allows users to use their phone number on any compatible Internet-connected smartwatch, tablet, or computer. Customers can get another Digits line for an additional $10 per month via AutoPay. Up to five numbers per device and up to five devices per number are supported. A qualifying plan is required.
There's a less expensive way, and then there's the way that works for you. The two may not be the same.