Zenith Number

A Zenith number is a special type of toll-free telephone number in the United States and Canada that was introduced prior to the development of WATS toll-free service. It allows a calling party to call the number's owner at no charge by dialing the operator and requesting the specified Zenith number. In some places the name Enterprise or the letters WX are used. Some organizations continue to keep their Zenith numbers - as of 2006, the California Highway Patrol continues to use the same single number it has for decades, Zenith 1-2000. But with the low cost of incoming WATS service, Zenith numbers have nearly disappeared and telephone companies in most service areas no longer offer new Zenith numbers.

The operator handled the call by looking up the regular number corresponding to the Zenith number, typically in a paper book kept at the switchboard, and completing the call as if it were a collect call to the regular number.

The reason the name Zenith is used is that the letter Z did not, at the time that the service started, appear on the telephone dial, thus necessitating that the caller dial the operator.