Toll free is a term used to describe something that is free of charge. According to Dictionary.com, the term is typically applied to roads or telephone numbers.
When the term is used in the context of phone numbers, it implies that calls are free for the party making the call, as all the associated costs are paid by the party receiving the call. Toll free numbers are popular, as they allow potential customers to find out about a business or service for free.
In the USA toll free numbers always begin with one of a number of specific three-digit sequences: 800, 888, 844, 855, 866 or 877. Toll free numbers that spell out the name of a company or service, such as 1-800-FLOWERS, are known as "vanity" numbers. Outside of the USA, toll free telephone services are known as free phone numbers.