Conversation so far:
how many digits in an irish phone number
Irish area codes vary in length, between one and three digits (excluding the leading 0), and subscribers' numbers are between five and seven digits.
what is the country code for ireland
The country code for Ireland is +353.
what is the country code for northern ireland
The calling code for Northern Ireland is +44.
is the calling code for the uk the same as northern ireland
Northern Ireland's country code is 44. This is the UK country code.

Question: who administers the country's telephone numbers
Self-contained rewrite: who administers the uk's telephone numbers