One common purpose for this service is to enable customers to retain their telephone number when they move to a location serviced by a different telephone exchange.
The service is useful for business customers with widely advertised numbers which appear on headed paper, vehicles and various marketing literature.
Another alternative is to port the existing number to a voice over IP carrier, which is not tied to a single physical location as the subscriber may be anywhere on broadband Internet.
In this respect, it differs from the (similarly named) Remote Access to Call Forwarding in that the number is attached to a physical line where it rings normally until a call is made to a remote number to enable redirection.
Remote Access to Call Forwarding allows incoming calls to be diverted and answered elsewhere if a subscriber cannot use their telephone normally (for instance, the number is assigned to a lost or stolen wireless handset or to a landline in need of repair service).