are you a BT Retail phone nas broadband customer? are you trying to get an old number back or trying to new number as having problems with existing number?
do you have digital voice?
I presume DV re numbers are no different to PSTN re numbers in that it’s a charged for service unless it’s being requested because of nuisance calls , and the police have been involved , AFAIR , it’s around £40.
Blocking incoming numbers is pointless as they're spoofed anyway & will change on every call. I suspect that changing the number will only provide temporary respite also. You really need to look at a system that will block unrecognised calls & force the caller to announce who they are.
Have a look at Truecall Secure, which can be managed remotely & can have unknown caller redirected to you. It requires installation of a small box on the line but no interaction from the user after that. But there is a subscription fee.
Unfortunately changing the number may not help, as all numbers are targeted by scammers. Blocking numbers will have no effect.
Although you have said that a new phone would not help, there are phones that block all numbers, apart from those that are wanted. These stop 100% of scam calls, and do not need any intervention by the end user to block calls.
Look at the BT4600.
Any number which is stored in the phone`s directory will be allowed, all others will be blocked, asked to announce themselves, or sent to the answer machine.
Scam calls are automated, and do not announce themselves.
The basic call protect does not give that option, you have to pay BT for the advanced version, not sure what its called, but I do know others have used it.
You would still have to check for calls that had been blocked, but should not have been, as they should have been added to the VIP list.
edit: its called
When you have BT Call Protect with a personal voicemail service of BT Answer 1571 or Call Minder, you automatically receive two additional features to manage your calls: