[dexter0]

Use a "proxy" phone number that forwards to your cell phone number and keep your real cell phone number private.

[jasonkostempski]

It's not the number that's a problem, devices are tracked and the data is sold by the cell provider. Even if it's not billed under your name, it's likely moving between your house and your work 5 days a week, that's enough to deduce who it's used by.