It links your smartphone to a PC or Mac via a website. And, using that website, you can send and receive standard texts with phones, regardless of what cellular network they are on, what operating system they use, or whether they have the app. You can also make phone calls from the computer using the linked phone’s number, even if the phone is off or out of juice.
http://recode.net/2014/03/18/new-app-turns-a-pc-into-a-calling-texting-virtual-phone/