Mobile Devices, Services and Mobile Applications managed by ITAM/SAM/TEM

This has perplexed me for a couple of years now and I am curious if there is an emergent way to holistically manage the mobile estate.

In the expense management space, the phone number associated with the device drives allocation and payment. Carrier invoicing does not care about the device. But Device Management and provisioning focuses on the device (IMEI) caring little about the phone number since the phone number can be changed at any time without impacting the device. To say nothing of the reality that you can associate the same phone number to multiple devices because of upgrades.

Has any figured out a way to solve this riddle.

Somewhat related. How well does SAM do with Mobile App licenses? Does it associate to the Device or the phone number?