I have used this site a few times.

Here is the main site
Melissa Data Corp


At the top of the page is

Free Lookups


on that page is lookups for everything from Area Codes to Zip Codes. I think it mostly US data.

It says

Results for Phone Number '781-738-0000'
Area Code: 781
Prefix: 738 Cellular
City: NORWELL
State: Massachusetts
Primary ZIP Code: 02061
Country: United States of America
County Name (FIPS Code): PLYMOUTH ( 25023 )
Time Zone (Local Time): Eastern ( 7/11/2003 11:36:45 PM )
Metro Area (Code): BOSTON-WORCESTER-LAWRENCE, MA-NH-ME-CT ( 1122 )
Primary Metro Area (Code): BOSTON, MA-NH ( 1120 )