Associate multiple phone numbers to a user & the use same phone number as a secondary phone number

It would be great to be able to associate multiple phone numbers to a single user profile to be able to recognize and call customers on a cell phone and a business landline phone number easily. 

It would also be great to be able to associate the same phone number (like a landline business number) to multiple user profiles so that you can select the user that is actually calling from a generic business number and conversations and CSATs will be properly associated and sent to the correct customer that is actually calling (such as a manager, business owner, instructor all calling from the same phone number at the front desk of a gym over time).