said by HeadSpinning:
Bell has a one time rental fee that they credit back. Not sure why they do it that way.
Because they can't give them away, but don't want to charge for them. They could rent them for $1.00/month and then give you a $1.00/month credit, or lower the cost of the connection by $1.00/month. But it is far easier on the books to have a single offsetting entry for each account.