Can you interchange 866 with another toll free number?

NO. Toll free numbers in the 800 line are not interchangeable.

Does this number work for voice communication only or is there  any other way it can be used?

A.866 toll free code works for both voice and fax communication.  Simply add the phrase “Phone+Fax” to your business cards and or website.

What is a vanity number and how can you get one?

A vanity number is a toll free number which includes your name or that of the company. It may also be an acronym or word chosen by you-the subscriber. An example may be 1-866-ZANNA ROSES this helps your customers and prospects to remember your business name and also increases brand visibility.