White, black and grey routes

In telecommunications business, a white route is a route where both source and destination are legal termination. This is opposed to a black route, which is a route that is illegal in both ends. Also common in telecom (especially VoIP) is the term grey route, which defines a route that is legal for one country or the party on one end, but illegal on the alternative end.

An example of the white/grey/black trichotomy is often seen in telecom routes from the United States to India. In India, a telecom oligopoly is granted to a few large corporations. Hence, all legal ("white") telecom traffic to the country is subject to the rates imposed by these corporations. To overcome this restriction for the purpose of achieving lower costs for consumers, and to make a profit in the process, many small parties set up VoIP routers in homes and offices around India. Telecom traffic from other countries is sent to these VoIP routers via IP and terminated to the local Indian PSTN. This process is illegal in India ("black"), but completely lawful in the USA ("white"). A route like this, white on one end and black on the other is said to be "grey".