One aspect is good! It is that the service to show CLI has to be free now. I like that part.
However. The other aspect is on various moves to try and make CLI more reliable. This is seems to make sense as junk callers often use invalid CLIs these days, e.g. 025 numbers.
But OFCOM have gone way further, insisting that CLIs should be valid and dialable, i.e. in service and can be used to make a return call. Now this is huge. There are loads of reasons you may not be able to make a return call :-
- Number is not valid / in service (what OFCOM want to catch)
- Incoming call barring (a valid service which currently does not stop CLI being sent)
- Incoming call diversion (to numbers that are not valid, etc, etc)
- Incoming call where caller is calling withheld and withheld is blocked (ACR)
- Incoming call where the called party has used some call refusal / blocking service
- Incoming call to a phone system which is able to reject the call (e.g. ISDN, SIP, etc).
- Incoming call that the called party rejects (e.g. to a mobile and press red/cancel button)
- Incoming call that the called party simply chooses not to answer
All of these are (or were) valid services to stop someone making a return call. However, taking OFCOM strictly at their word, if any of these are in place as a service (such as incoming call barring) then the calling telco should not send CLI or possible not allow the original call, because the CLI is not one that can be used to make a return call!
It is also unclear why OFCOM decided to go this far. There seems to be some merit in expecting some basic validation, maybe, but even that may have problems. That can be done in various ways, but if considering international numbers you suddenly present the telcos with the job of maintaining lists of all valid number allocation blocks for the whole world, a complex tasks, or relying on some 3rd party to do that, placing them in a position of power if they decide not to include some block of numbers in the CLI allow list and hence not allow calls. It creates lots of scope for consumer problems, which already exists with new number blocks not routing to their destination - now we face a separate hell of new number blocks unable to route outgoing calls as the block is not in CLI allow lists.
But, even if we have that, we have already seen junk callers go from withheld to invalid prefixes. They will now simply move to valid number blocks and there will be ways to get those in to the phone network I am sure. This will create something called back-scatter. Oddly I have already seen these where junk callers are using invalid numbers as I have some 0200 numbers (which would normally count as invalid), and I suddenly started getting calls from people saying I had called them trying to sell them something. It was not pleasant, not matter how much I tried to explain (and I knew what must have happened). I had to turn off one of my numbers for this. Now consider what happens when junk callers move to using real numbers that belong to innocent victims. This will be bad.
One reason calls will get in is that a telco / carrier cannot easily verify the CLIs of calls. We are a small telco and we will be able to send any CLI we choose, not just from our number blocks. (Obviously we are strict with our customers and follow rules) But the reason we can send any numbers is (a) presentation numbers and (b) forwarded calls. If a call comes in to us from telco A and we forward at our customer's request on to a number which we send via telco B, then telco B has to trust we are sending a sensible CLI even though not one of our numbers or a call they see coming in to us.
So junk callers need to make calls from the OFCOM press office direct line CLI as much as possible, that way OFCOM will understand the issue of back scatter. [OK that is an illustration, and I am not actually trying to incite people to do that].
If anything, better education that CLIs can, and are, spoofed, would help. It is just the same with email addresses. (educating police on this fact is a good idea too!)
Sorry OFCOM, I think you have massively missed the mark here, and could cause legitimate services like incoming call barring to impact CLI for no reason, and cause back-scatter on junk calls, whilst not actually addressing the real problem.