@Bluesplayer there is a large precentage of the customer base that does not use a landline phone service. To setup and support a voip service would be likely not be cost effective for the small percentage of customers that would wish to use it.
As @jab1 has indicated , BT group as a whole have determined that the cost effective option is to offer to transfer those customers who require a combined broadband and digital voice service to EE.
Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.