mathematics

Telephone number verification

Telephone number verification is a mathematics 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 Telephone number verification rather than just read about it. In short: Telephone number verification (or validation) services are online services used to establish whether a given telephone number is in service. They may include a form of Turing test to further determine if a human answers or answering equipment such as a modem, fax, voice mail or answering machine.

Key takeaways

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

Reference excerpt

Telephone number verification (or validation) services are online services used to establish whether a given telephone number is in service. They may include a form of Turing test to further determine if a human answers or answering equipment such as a modem, fax, voice mail or answering machine.

Purpose Verification services are often used to limit sockpuppetry, underage sign-ups, spamming and illegal activities like harassment, scams and fraud. Operators and their clients include:

Lead generation companies Social networking sites Internet forums dating sites and wikis Any verification operation which sells sets of contact numbers generated through its marketing operations will gain a premium for an efficient list of “clean” numbers. Call center outbound telephone campaigns save time and resources bypassing undefined or mechanized equipment numbers.

Telephone numbers entered into an online sign-up form can be checked in real time, by implementing AJAX (background web page processing) type call to a telephone number verification service while the form is still being filled in. To thwart fraud, it is possible to match an online customer to the telephone number owner, to certify it is in fact the same person who owns it. This service is of increasing value to online store managers, banks and credit card processors, who are faced with increasing quantities of attempts to make fraudulent purchases such as by those using stolen credit card details.

Methods employed

Line test An aborted call is made to the subscriber line. This automated service “listens” to check for ringback tones, busy signals, answered call, voice mail automated answering, or network operator injected messages such as “the number called is not in service”. This method benefits from being international and covering mobile phones. However, the check can take up to 30 seconds to complete (average time 9 seconds). This delay can be handled well by the use of AJAX background processes for example by allowing the user to continue filling in other fields in a form while the line test is performed.

Turing test It is possible to employ such methods further to verify that genuine people answer the telephone at that number by requesting a key press tone "Press one to 'unsubscribe'." Often this method is used to clean lists, and rather than unsubscribing, the number is categorized as a live one.

Line test + authentication To verify that a telephone number exists and authorize its use, subscribers supply a telephone number on which to establish service, often via a web page. A unique code is first indicated or displayed to the customer via the web site, then an automated call is then placed to the supplied subscriber telephone number. To validate the transaction, the code entered via the Telephone Keypad must match. This method is used by Google Voice and online banking services such as Lloyds TSB.

Database check Certain services offer to check telephone numbers alongside other personal details, gained from various public sources e.g. the Electoral roll and from the imprints left on by their activities, for examples from transactions made using credit cards. The advantage of a database check is that the lookup can be very quick (sub 1s), however no databases exist to cover all telephone subscriber lines internationally, with mobile telephones being particularly problematic to trace - especially Pay as you go (phone) (non contract) arrangements which often have no registered owner. Some databases are very detailed and can correlate telephone numbers with physical addresses, e-mail addresses, ownership and sometimes even personal details. Such detail can help with combating fraud as well as allowing greater understanding of a customer base. At the other end of the scale, other database checking services might only check a telephone number against the allotted telephone number banks and therefore only indicate if a number is in a range that might be active and are therefore inconclusive.

Check for valid number format A JavaScript function can check to see if a phone number is a valid format, i.e., is numeric, starts with a valid set of numbers ("0" for local, or an international dialing prefix followed by a valid country code) and is not too short to be a phone number. At first a JavaScript function is used to clear out any spacer characters. Next, a function is employed to check if the phone number contain only numbers, last the length of the string is checked permitting only phone numbers with an allowable number of digits for the country. It is prudent to carry out such checks even if a further method is employed in addition, so that telephone numbers to avoid wasting time and resource on numbers that are clearly not in a correct format to qualify as a telephone number, e.g. too short.

Other methods of verification Some other methods that are being employed today are:

Sending an OTP via SMS or IVR call is also used by a majority of companies, wherein the user has to enter the received to confirm the identity. User being asked to dial a number or a send a message which helps the server identify that the number is genuine and valid. With the advent of smartphones, type 0 or type 1 SMS are also being employed to send the codes which are used to verify the genuine user. Soft tokens generated within the smartphone or push messages can also be used.

References

External links Global Phone Format Validation

Worked examples

Example 1 — a first encounter with Telephone number verification

Start with the simplest possible case. Write down what Telephone number verification claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, 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 Telephone number verification 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 Telephone number verification 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 Telephone number verification

In research: Telephone number verification appears in mathematics 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 Telephone number verification 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: Telephone number verification is common in secondary-school and first-year university syllabi. It links to neighbouring topics Telephony, so understanding it makes those chapters shorter.
In everyday life: Look for Telephone number verification 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 Telephone number verification in 20 minutes

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

Frequently asked questions

What is Telephone number verification in simple terms?

Why does Telephone number verification matter?

Because it connects several mathematics 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 Telephone number verification?

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 Telephone number verification.