+44 (dialed as 00 44 from many places) is the country code for the UK - the digit 7 indicates the number belongs to a mobile (cell) phone (+44 74 through +44 ...
All international calling codes featured in one place.
The country code 44 is for the United Kingdom. The 7 indicates that it is a cell phone. If you were calling 447, you would be dialing a cell phone number in the.