The format is 0 followed by 9 digits: that is my area code of 01276 plus five digits. I think you are calling a number that is 0 plus 10 digits.
VM claim that this a standard format which is a very partial way of looking at it. Telephone numbers have been all sorts of formats over history that have become fixed into the systems in place. In such an environment it seems silly to use a fixed length format.
However we are where we are and it seems unlikely that VM will change its software and even less likely that they will stop promoting SmartCall to someone who cannot use it.
Perhaps you should have said in your original post that you could not register for Smartcall, rather than "I have tried to use SmartCall but it will not accept the phone number".
AFAIK the registration code must be sent to a standard mobile number (preferably the mobile using Smartcall) & not a landline. This is because caller ID shown when you make a call is then tethered to that number.
Cable customer since 1993. Services: FH TV, Sky Sports & Movies (2xV6), Talk Anytime Phone, VIVID 350, Virgin PAYG Mobile
Correct so far. When you have the code you provide that to the registration page. It then asks for your telephone number. Presumedly to access the account details.
My telephone number is not long enough.
I have been a VM customer since way back when it was NTL. We used to have an irritation in that it used to ask for the phone number or enter zero followed by the account number.
It never recognised my phone number. I was told by one VM person that they enter an additional zero at the beginning of the number to access the record. Obviously not available to me as that then required me to remember my account number.
The irritation has gone away it that it now asks if the phone I am calling from is the one on the account. Now I can remember the answer to that question!