"At least one mobile number is not recognizable." But, numbers are

[Sabermist]

"At least one mobile number is not recognizable. Check the mobile numbers,
and then try again."

I have set up outlook mobile notifications. I can run the test, and the
message arrives on my phone, but when i go to set up calendar notification
forwarding, it gives me the error message "At least one mobile number is not
recognizable. Check the mobile numbers, and then try again." I have set it up
the same way that I did on another computer, which works fine, what's the
deal with this one?