To add a device, you need someone to pick up the phone, and dial the **5 + 4 digit number as presented by Obitalk.
So the answer is yes, if you can have "someone" to dial those digits remotely. And NO, if the device is sitting remotely unattended.
The intent is to add your own device that you have "physical" access to. The OBi number is not so secret. Just by knowing your OBi No - you don't want someone else to suddenly "capture and own" it, right?