It's possible that the SOS button won't work anyway cos there's no coverage in ur area as none of the mobile operators are contracted to BMW AG.
The number stored in the system should be a German call centre number, & when the car is outside of Germany it'll call that number via a roamed mobile network. I think BMW AG only has roaming agreements with countries that offers the Assist service.
Teleservice is just for sending data back to the home country, so that if anything's wrong, e.g. u're approaching ur next service appointment, then the call centre to call u to alert u of the problems.