science

White, black and grey routes

White, black and grey routes is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand White, black and grey routes rather than just read about it. In short: 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.

Key takeaways

White, black and grey routes belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect White, black and grey routes to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of White, black and grey routes from memory before moving on to harder problems.

Reference excerpt

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".

SIM boxes A "SIM box" is an unofficial voice over IP gateway which uses multiple mobile telephones and SIM cards for PSTN connectivity, while connecting to the Internet by conventional means. These are normally operated clandestinely in third-world calling destinations as the "black" end of a "grey route" where conventional private branch exchange lines (such as T-carrier primary rate interface) are not available to VoIP operators due to a hostile local regulatory environment. In India, for instance, an Internet Service Licensee is not permitted to have PSTN/PLMN connectivity as voice communication to and from a telephone connected to PSTN/PLMN and following E.164 numbering is prohibited in India. By using licensing restrictions and regulations to ensure that the interconnection between the PSTN/PLMN network and Internet is not permitted, the government in India delivers a lucrative monopoly to International Long Distance (ILD) service providers licensed under Section 4 of the Indian Telegraph Act as the only carriers officially allowed to carry international long-distance traffic into India.

Worked examples

Example 1 — a first encounter with White, black and grey routes

Start with the simplest possible case. Write down what White, black and grey routes claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to White, black and grey routes before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about White, black and grey routes ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of White, black and grey routes

In research: White, black and grey routes appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses White, black and grey routes in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: White, black and grey routes is common in secondary-school and first-year university syllabi. It links to neighbouring topics Telephony, Voice over IP, so understanding it makes those chapters shorter.
In everyday life: Look for White, black and grey routes outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study White, black and grey routes in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what White, black and grey routes means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain White, black and grey routes out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is White, black and grey routes in simple terms?

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.

Why does White, black and grey routes matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study White, black and grey routes?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on White, black and grey routes.