Why is my left arm slightly shorter than my right? I dunno. But I do know that there ARE remotely controlled robots via the internet (which includes WIFI, which includes cell phone). The concept of controlling any device with a cellphone has to utilize either the bluetooth (and good luck getting access via SDKs unless googlephone and i could be wrong about that since it's been a while since i bothered to find out if apple or microsoft were yet willing to allow control of bt via sdk) which is relative short range or the wifi which is still limited to the addressing problem inherent in the ip address space (ie, what's the ip address of the device you are trying to control-- assuming it's outside your local area, otherwise why not BT?).
Normally, such a project as controlling a device via the "general network" if you will, requires a fixed address scheme or registration process.
I've been toying with the idea of a registration server for just this purpose. Anybody interested in developing a new protocol?
If you meant the robot would have a phone number, would respond to the ring, don't know, but bet it has been done.
No real value in old technology (unless you find a rare VFD tube worth 40 bucks...