[cynwoody]

There already is one. . .

US $44.00 / piece
Minimum order 10 pieces

From Shenzhen JOYSAVE Technology Co., Ltd., founded in 2013.

http://www.alibaba.com/product-detail/2014-Newest-Smart-Bluetooth-Watch-GV08_60136483283.html

[amigatec]

I think more of the problem is with the Cell Service Providers. My iPhone and iPad are both ATT. My iPhone has the primary account and for $10 a month, my iPad has been added to the account. Both have a Phone Number, but I can only make Phone calls with iPhone, with iOS 8, I can now “piggyback” off of the iPhone and make and receive calls using any of my Apple devices as long as I'm on the same WIFI network. Same goes for text messages to any phone other then an iPhone. The phone calls and text messages show that they have come from my iPhone number.

I'm not sure how the Cell Providers would handle this. I don't know if they could allow more than one device to use the same number without some changes to system. Also how much would people be willing to pay for all of this.