I recently enabled two-factor authentication everywhere I could, and many sites now text me when I log in. Nearly every company texts from a unique number, as I would expect. However, Microsoft and LinkedIn always text me from the same number (i.e. same as each other).
Does anyone know why?
Does this just say that Microsoft and LinkedIn are hiring the same third party to manage their two-factor?
Is there something more interesting going on there?
I don't know where you're located, but in my corner of the world, this is not unusual.
If you wish to push text messages, you will need to sign up with an SMS service provider. You can reserve a short, 4-digit number for your services, which is expensive.
Or you can reserve a keyword within a 4-digit number. The number is then shared among other services, which is a lot cheaper.
I'm guessing Microsoft and LinkedIn are simply using the same SMS service provider. As they are not (?) allowing users to respond to their messages, they don't need to reserve a short number.
So the answer to your question is: They may not be using the same third party to manage two-factor authentication, but they are using the same third party for SMS services.
