If you have asked VM to port the phone number you have with BT , onto VM , then by them requesting the port , as the number is associated with your ‘line’ , it will be ceased , and assuming your BT line and broadband are on the same account , the broadband will be ceased as well , as a consequence of the line ceasing ( broadband cannot exist if it’s host line is ceased ) if this is the case you leave it to VM .
If you are not porting the number , or somehow your BT line and BT broadband are on separate accounts you need to advise BT yourself when you want the broadband to cease giving 30 days notice if out of any minimum term contract.
