Finite number of mobile numbers.

  DANZIG 12 Apr 11

I had a thought earlier.

A mate of mine changed his mobile number just by phoning his operator who gave him a new number over the phone, quite impressive service I thought. However there must be a finite amount of numbers out there to be used, I haven't done the maths to work out how many that finite number is, but it IS finite. his OLD number simply reused by someone else or discarded??

If it is re-used, wouldn't that cause privacy issues if the number was given to an -ex-contact (for example) of the phone owner?? Admittedly it would have to be an incredible coincidence though.

If its discarded - when are the numbers available going to run out? Then what??

  Woolwell 12 Apr 11

I think that they may reuse the number after 6 months. I've always taken my number with me.

  Proclaimer 12 Apr 11

18 months is the turn over time.

  rdave13 13 Apr 11

Can anything be finite in mathematics? A mobile phone number might be reused but I can't think of a reason to.

  DANZIG 13 Apr 11

My point is that the phone number of length 11 digits can only have so many permutations, albeit a hell of lot of them. If numbers are not reused then eventually what with more and more people getting mobile and an increasing population, eventually they will run out.

Just like, I believe in the early 90's, when landlines got an extra digit.

The difference being, a landline is attached to a dwelling, whereas a mobile phone is attached to a person.

  bremner 13 Apr 11

Currently all uk mobiles start 07

This gives a total of 1 billion (1000 million) numbers. With a population of about 60 million this does seem sufficient.

  spider9 13 Apr 11

11 digits, each one could be any one of 0,,1,2,...9 (that is ten digits) so in theory 10X10X10....eleven times.

Numbers available 10 000 0000 000. World population about 6 billion = 6 000 000 000 (using defn of billion as a thousand million).
So should be enough numbers?

  DANZIG 13 Apr 11

Well the maths seems to be OK, but how about this....

I'm on my 5th phone now, and the first one I've had a contract with, the rest were pay as you go.

Those earlier phones I gave away to charity in those 'old phone collection schemes' some of them do. Will those phone numbers get re-used or are they still attached to those phones??

I can't be the only person who has done this, say a million people have done the same as me - thats 4 million numbers floating around unused (maybe).

  spider9 13 Apr 11

But on the worldwide scale there are at present 4 billion 'spares', and that's assuming every man, woman and child in the whole world had a mobile phone. Even using your example of 'a million others.. like me' would hardly make a dent in 4 billion.

  BT 13 Apr 11


When you gave away the phones did you not remove the SIM cards? The number is attached to the SIM card not the phone.

Regarding the number of numbers in circulation, I got 4 free SIMs from T-Mobile when I needed one for a phone that had been given to my wife. Each SIM has its own number so that's 3 numbers that are not being used. When you consider the vast numbers of free SIM cards being given out in multiples by the providers, there must be huge numbers of numbers just sitting there not being used.

  bremner 13 Apr 11


Your figures are somewhat out.

Just assuming every country in the world used 07 as the start of their mobile numbers as we do then each country would have 1 billion numbers available.

Each country of course has its own International Dialing code so someone in the US would have exactly the same 07x number as me in the UK.

How many international dialing codes are there 100 ish which gives 100 billion numbers


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