Why does a call from abroad, Ireland in this case, show as 'Withheld' on my BT2100 home phone but on my BT Protect account the full Irish telephone number is shown?
I do not answer calls from withheld numbers but would have answered this call if I had seen the number displayed.
I suspect that the caller has actually withheld the number, but this only affects how the number is presented at your local exchange.
Incoming to the BT network, this number will still be visible, as are all numbers where the caller has withheld their number. This is how BT Protect is effective.
Withholding your number only affects how its displayed at the destination, so emergency services can still see your number, even if you have withheld it.