Hello did you get sorted with this? It appears O2 haven't changed they way this works for smart watches unfortunately. Other networks allow you to use the same number on both the phone and watch at the same time but O2 is using the lazy method of using Samsung's Calls & Texts on other devices setting, which is exclusive to Samsung phones etc, so if you have another brand of phone any calls and texts from your phones number won't be received on the watch unless you're connected nearby on Bluetooth to the watch. O2 need to advertise this on the listing for the watches they're selling.
