mathematics

Personal numbering

Personal numbering 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 Personal numbering rather than just read about it. In short: Personal numbering is the name for the virtual telephone number service in the UK. Typically the national destination code used for this service is 70, dialled as 070 from within the UK and +44 70 from outside.

Key takeaways

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

Reference excerpt

Personal numbering is the name for the virtual telephone number service in the UK. Typically the national destination code used for this service is 70, dialled as 070 from within the UK and +44 70 from outside. The service provides a flexible virtual telephone number able to be routed to any other number, including international mobiles. For example, the UK number +44 70 0585 0070 might route to an Inmarsat satellite phone number, allowing the user to have a UK number while roaming globally.

History In the United States, AT&T ran a trial in 1991 which led, in 1992, to the AT&T EasyReach 700 service of follow me numbers, on area code 700.

Early days After protracted lobbying of Oftel throughout 1992, FleXtel launched the UK's first Personal Telephone Number Service, using the 0956 7xxxxx number range in December 1993, within the old One2One 0956 xxxxxx mobile number range.

070 introduction In 1995 the UK telecoms regulator, Oftel (now Ofcom), moved geographic area codes starting 0x1 to new 01x1, and starting 02xx to 09xx to new 012xx to 019xx, thus freeing many of the former 02xx to 09xx codes for new uses. Oftel reserved the whole of the 070 xxxx xxxx range exclusively for personal numbering, imitating the USA area code 700. FleXtel migrated its existing customers from the old 0956 7xxxxx numbers to new 070 107x xxxx numbers during a two-year transition phase, ending 28 April 2001.

Fraudulent use For two decades this service was plagued with "significant scamming activity" of various sorts as users can mistakenly assume they are calling a UK mobile telephone number that generally costs far less.

(For the telephone numbering plan context of 070 numbers see Telephone numbers in the United Kingdom).

Call cost scams A range of scams revolve around UK residents being tricked into making calls to 070 numbers that attract much larger than normal call costs.

False UK number scams In its full format (e.g. +44 70 0585 0070) an 070 number will be internationally recognisable as a UK number - even though it might in fact terminate to a mobile number anywhere - this feature is used in a variety of scams.

Ofcom reforms Concerned at the number of scams, Ofcom consulted on removing revenue share from the 070 range and this took effect in 2009. They had previously considered other options such as moving this service to the unused 06 number range or enforcing a pre-call announcement of the call charges. Although consulted on, those other remedies were never put into effect. Concerned at the lack of transparency and the high retail charges for calls to 070 numbers, Ofcom launched a call cost review in 2017. This led to a consultation in 2018 which recommended capping the termination rate or wholesale rate at no more than the rate for calling a mobile number. Those changes took effect on 1 October 2019 and several phone providers have already passed the saving on by now including calls to 070 numbers within inclusive allowances. It is reported that scams on this number range fell by 75% in the year following this change.

See also Personal Numbers, similar service in Spain Area code 700, similar US service Follow-me, similar concept for PBXs Virtual number Universal Personal Telecommunications

References

Worked examples

Example 1 — a first encounter with Personal numbering

Start with the simplest possible case. Write down what Personal numbering 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 Personal numbering 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 Personal numbering 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 Personal numbering

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

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

Frequently asked questions

What is Personal numbering in simple terms?

Why does Personal numbering 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 Personal numbering?

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 Personal numbering.