To find a telephone directory for any country in the world, try Telephone Directories on the Web and howtocallinternational.com. For help in dialing from one country to another try countrycallingcodes.com.

The most popular sites for the US and Canada are organized into the following table for quick reference.

  Telephone Number Locators

	Person	Business
	whitepages.ca (reverse number look-up) superpages.ca (reverse number look-up) yellow.ca (reverse number look-up)	whitepages.ca (reverse number look-up) yellow.ca (reverse number look-up) yellowpages.ca (reverse number look-up)
	AnyWho (reverse look-up) daplus.us (reverse look-up) findlaw.com (reverse number look-up) Superpages.com (reverse number look-up) whitepages.com (reverse number look-up)	AnyWho (reverse number look-up) daplus.us (reverse number look-up) findlaw.com (reverse number look-up) superpages.com (reverse number look-up) whitepages.com (reverse number look-up)

Note: Google has a built in U.S. phonebook. I've gotten mixed results for Canada.

Reverse Number Look-up - Who does that number belong to and where do they live? To find out, use the look-up links in the above table. Tip: If a search for a business number comes up negative, round the number to the nearest even hundred. You may find no information for 734-1234, but 734-1200 may be the switchboard.

Reverse Area Code Look-up - Try Verizon, yellow.ca, cnac.ca (area code map for Canada), areacodeworld.com (free demo), telcodata.us or Americom's Decoder.

• ZIP, City & Phone Lookup - Enter ONE of the following:  ZIP Code, ZIP+4, City, Phone number or Area Code

• Area Code + Prefixes in a Radius - Give it a phone number (3 to 10 digits), EG 973-616-6456
  and it will display all the phone prefixes with a given distance (five miles, for example).

• calling-plans.com - Area Codes and Area Code Information

Reverse Look-up Fax Numbers - Try Findlaw (US only).

Reverse Look-up Toll-Free Numbers - Try 1-800 Toll Free, 1-800 (Findlaw), or AnyWho.

Reverse Look-up Cell Phone Numbers - The situation may change in the U.S., but there are currently no directories for cell phones like there are for regular land lines.¹ The only thing you will find on the Net are:

• opt-in sites such as cellphonedirectory.com where people voluntarily submit their numbers and

• commercial sites such as intelus.com which may capture a cell phone or unlisted numbers from public record documents.²

Location and Carrier - If a phone number cannot be found through a regular reverse look-up, it may be unlisted or a cell phone number. If so, you can still use the first six numbers to find out where the number was issued and the name of the telephone company which owns the prefix. Once the company is identified, an investigator can obtain subscriber information with a court order.

Note: Recently, number portability was approved in the U.S. (but not in Canada). NationalPooling.com is a site that tracks ported numbers. It is only available to law enforcement.

• Central Office Code Utilized Report - Select a state and area code, and it will show you who owns a block of numbers. Part of nationalnanpa.com, the group the coordinates number distribution so it is more up-to-date than other sites.

• FoneFinder - Type in area code and prefix. Provides general location and name of local telephone company. Covers US, Canada, and International numbers. Similar to melissadata.com and thedirectory.org. Caution: May be out of date. 

• Prefix Numbers by Area Code - Click "List of Area Codes" then on the area code you wish to search. All prefixes within the given area code will be displayed along with the assigned carrier, E.G. Telus. By the name of the carrier, you can also tell if belongs to a cell phone.

• International Numbering Plans - worldwide phone numbers, network IMSI numbers, handset IMEI codes, SIM card numbers, as well as international signalling point codes.

• SearchBug.com - Verify if a phone number is a cellular number or a regular (home or office) land line number

• Another option: Call 800-337-4194. Key in the number. The automated system will instantly identify the RespOrg (responsible organization,i.e., the carrier).

Old Phone Numbers - Some public libraries, skip tracers, and genealogists keep old phone books and Crisscross Directories. The British Columbia Genealogical Society, for example, has a resource centre in Surrey, B.C. filled with old phone books from across Canada. If you know that the person you are looking for lived in Calgary in 1986, such places might be able to dig up an old address for the person. If you want to know who had a particular phone number in 1998, an old crisscross directory is the place to look.

Investigators may wish to examine:

• old phone books to develop an address history for a person and

• old crisscross directories to determine who had a certain telephone number at a particular time, E.G. the subscriber for 416 555-1234 in May 2002.

Phone Records - Many sites on the Internet claim to be able to obtain records of a person's telephone calls. Since the telephone companies hold these records, the only way for someone to sell such information is for them to obtain unauthorized access by pretending to be the subscriber, bribing someone who works for the phone company or hacking into a subscriber's online account. Such sites are usually less than candid about their tactics.

• Twenty Five Little Known Telephone Tips for Private Investigators, By Ralph Thomas. "Most people think that the standard weapon used by most private investigators is a gun. The fact is, the most powerful weapon a private investigator uses is the telephone." - A lot of product advertisements, but a few useful tips as well.

• Can we tape? A State-by-State Guide by the Reporters Committee for Freedom of the Press.