If you have as many mobile phones as you have products, another tracking solution that is currently available is members of an organization, where you invite an email address.
Here is a link to a script that shows the endpoint that can be used to track organization user usage: https://github.com/dav-ell/toktrack.
(edit, this function of accessing undocumented APIs by your API key has been removed)
I won’t post the topic it came from because it has a dangerous website linked - (which can be described as “put in your API key for us to steal, and we’ll block showing our own abuse in our tracking until it’s too late”)
It is ridiculous and anti-enterprise to require unmanaged accounts that are validated not against your organization but by a phone number and their own credit card; that each phone number can only be used twice and account deletion renders the phone number unusable. The whole system should be trashed and re-thought.