If you train for a marathon with a SmartWatch connected to a wireless network you can leave your phone at home and still receive calls and notifications, but your mom will know which phone number to call?

AT&T announced a solution to this problem. At Wednesday the operator presented its NumberSync service linking telephone numbers of the various devices connected to a client on its cellular network under a single number. After the user linking devices the first time you need to remember and share a new number. All devices are synchronized via the cellular network and at the same time receive calls and notifications.

AT&T says NumberSync will be enable this Christmas.

Meanwhile, T-Mobile and Sprint, the No. 3 and No. 4 Wireless carriers in US, confirmed Thursday that also seek to offer a similar service to its customers. Verizon, the country’s largest phone carriers has not informed whether plans to offer the same function.

The NumberSync service has been developing for over a year and was named Cascade Project. The idea came from an employee of AT&T wanted to connect SIM cards from cars connected to a parent cell. The idea grew to include technology devices apparel, explained the engineer Erik Sundelof during a visit in January 2015 Innovation Center AT&T Foundry in Palo Alto where Cascade born. This center is one of four that has AT&T, with internal and external ideas, products that enhance the capabilities of the company and the consumer experience develop.

“It is heavy change phone numbers, many people like to have one number, and link [device] over a cellular network adds safety,” then he explained Sundelof adding that phones have to be able to work over LTE (VoLTE) and will not need Bluetooth, Wi-Fi or NFC.