Perhaps you can clarify, in your first post you state you have cancelled your BT broadband, but then state you have kept your BT line ?, are you saying you now only have ( and pay ) BT for line rental and calls , and either don’t have broadband at all , or have broadband from a totally different network ? or do you incorrectly think that if you pay another provider that uses Openreach it’s still a ‘BT’ line ?
Historically your phone number was an easy way to locate your account information, but you now can have BT broadband without any phone service at all ( so no telephone number is provided ) obviously in those cases asking for a phone number won’t serve any purpose, hence needing another method , like your BT ID , if you still have BT telephony without any BT broadband, then your number should still ‘find’ your account, but only if you are a current BT customer for telephony.
