science

Interexchange carrier

Interexchange carrier 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 Interexchange carrier rather than just read about it. In short: An interexchange carrier (IXC), in U.S. legal and regulatory terminology, is a type of telecommunications company, commonly called a long-distance telephone company. It is defined as any carrier that provides services across multiple local access and transport areas (interLATA).

Key takeaways

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

Reference excerpt

An interexchange carrier (IXC), in U.S. legal and regulatory terminology, is a type of telecommunications company, commonly called a long-distance telephone company. It is defined as any carrier that provides services across multiple local access and transport areas (interLATA). Calls made on telephone circuits within the local geographic area covered by one local network are handled only by that intraLATA carrier, commonly called a local telephone exchange carrier. Local calls are usually defined by connections made without additional charge whether the connected call is in the same LATA or connects to another LATA with no charge. IntraLATA usually refers to rated or toll calls between LATA within state boundaries, as opposed to interstate, or calls between LATAs in different states.

Call handling An interexchange carrier handles traffic between telephone exchanges. Telephone exchanges are identified in the United States by the three-digit area code (NPA) and the central office prefix, which is the first three digits of the local telephone number (NPA-NXX). Different exchanges, or central offices, generally serve different geographic areas. For voice traffic transfer, IXCs use Tandem switches and SS7 signaling or softswitches and VoIP protocols and error correction ITSPs can thereby connect between VoIP to POTS, computer to computer, computer to phone, and Internet Protocol devices to other phone services.

Carrier identification code Each carrier (interexchange or local exchange) is assigned a four-digit identification code, the carrier identification code (CIC) which was used with feature groups. The interexchange carrier to which calls from a subscriber line are routed by default is known as the presubscribed interexchange carrier (PIC). To give telephone users the possibility of opting for a different carrier on a call-by-call basis, carrier access codes (CAC) were devised. These consist of the digits 101 followed by the four-digit CIC. The CAC is dialed as a prefix immediately before dialing a long-distance telephone number. In popular usage, CACs are often referred to as dial-around codes, because they allow "dialing around" the PIC. Sometimes they are even called "PIC codes", though this term is inaccurate, since the code is being used to avoid the PIC, not to use its services. When CICs were first introduced in 1983, they were only three digits long, and the CAC consisted of the digits 10 followed by the three-digit CIC. In 1998, the CIC had to be extended to four digits. Existing carriers' codes were prefixed with 10. Thus, a pre-1998 CAC of the form 10-XXX became 101-0XXX. Since the CACs starting with 10-10 are generally the oldest and best-known ones, CACs are sometimes referred to as 10-10 codes.

See also 10-10-321/10-10-220 Long-distance calling Telephone slamming

References

FCC FAQ - Carrier Identification Codes (CICs) and Seven-Digit Carrier Access Code (CAC) Dialing

External links https://www.nanpa.com/ https://www.nanpa.com/numbering/carrier-identification-codes-cic

Worked examples

Example 1 — a first encounter with Interexchange carrier

Start with the simplest possible case. Write down what Interexchange carrier 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 Interexchange carrier 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 Interexchange carrier 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 Interexchange carrier

In research: Interexchange carrier 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 Interexchange carrier 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: Interexchange carrier is common in secondary-school and first-year university syllabi. It links to neighbouring topics Telecommunications companies, Telephony, so understanding it makes those chapters shorter.
In everyday life: Look for Interexchange carrier 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 Interexchange carrier in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Interexchange carrier 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 Interexchange carrier out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Interexchange carrier in simple terms?

Why does Interexchange carrier 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 Interexchange carrier?

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 Interexchange carrier.