This is a BT Consumer forum so the ‘advice’ here is based around someone in a residential setting , if you are a ‘proper’ BT Business customer ( and not a smaller business that uses a regular domestic service for their business , plenty of smaller businesses seem to do this ) what BT Business do may be different to what the BT consumer division does , so any advice here may be way off , the business division and their forum would be better in that case .
Obviously your set up , switchboard , multi lines , extension numbers if you have them , are going to need more consideration than a phone moving from a socket on the wall to the socket on the router , I doubt wether they will arbitrarily switch your service to fibre without your consent , but may push for you to make the change sooner rather than later .
