My father has a VoIP number, is this considered a landline number and if he was to switch to a broadband only contract would he loose his number?
Welcome to this user forum for BT Retail phone and broadband customers.
If you are referring to a phone service delivered by BT Digital Voice, then moving to a broadband only contract would cease that number and it cannot be recovered.
If you mean a third party VOIP number, then that would not be affected.
if by having a VOIP number your father has digital voice then moving to broadband only will lose his DV VOIP number unless ported to separate VOIP provider