With SMPF, the non-incumbent service provider could purchase wholesale the voice service provision from the PTT/ILEC to allow the former to control the customer relationship for both broadband and voice services. In the UK at least, this service is called Wholesale Line Rental (WLR).
In the context of SMPF, a non-incumbent service provider can acquire wholesale voice service offerings from the PTT/ILEC, enabling them to control customer interactions for both broadband and voice services. This practice is commonly referred to as Wholesale Line Rental (WLR) in the UK.