If you need to know the subscriber name and address for a telephone number try using Phone Search Central. From my experience they run a reputable business and will be able to get you the results you're looking for. They have a similar service to reverse lookup UK based numbers at www.phonesearchcentral.co.uk.

The phone number geolocator allows you to quickly find the geographical area that a phone number originates from. Locations are identified by matching the area code (NPA) and prefix (NXX) of a phone number to a latitude/longitude coordinate. This tool currently supports most phone numbers within the United States. The database is a little dated, so information such as whether the number is a landline or wireless may be inaccurate. Queries are confidential and are recorded for abuse prevention and statistical purposes only.

Most popular area codes: 818, 310, 212, 416, and 905.

I host YouGetSignal.com with MediaTemple. They have 24/7 support, great response times, and can best of all they can handle the Digg effect. If you decide to use them as well, do me a favor and list "yougetsignal.com" as your referral domain.