Finite number of mobile numbers.

  DANZIG 21:54 12 Apr 2011

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 22:44 12 Apr 2011

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

  Proclaimer 23:14 12 Apr 2011

18 months is the turn over time.

  rdave13 00:10 13 Apr 2011

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

  DANZIG 07:30 13 Apr 2011

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 07:51 13 Apr 2011

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.

  DANZIG 08:20 13 Apr 2011

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).

  BT 08:45 13 Apr 2011


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 08:45 13 Apr 2011


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

  interzone55 09:46 13 Apr 2011

Mobile numbers are re-used, as long as a number is cancelled it will be re-used after about 6 months, but there's an awful lot of Pay As You Go numbers that will never be re-used as the number isn't cancelled. I've got an emergency phone with about £5 of credit in my glove box, every few months I power it up and call my other phone to keep it live.

Regarding one billion numbers being enough for 60 million people, in theory that should be enough, but many people have two phones (personal & work, wife & girlfriend etc), and mobile phones aren't the only devices that use a SIM with an 07 number.

At my last house there was an electric gate. The gate had a controller that contained a SIM so I could call the gate and it would open. Useful because if I had a delivery the courier could ring me and I'd then be able to open the gate from anywhere.

Many intruder alarms now have cellular modems so they can contact monitoring centres if the phone line is cut, and some of the cameras you see along the motorways have 3G modems built in to send snap shots of traffic conditions every 5 minutes or so (the cameras that are constantly streaming are linked either by fibre or Wireless with repeaters, a 3G signal is not reliable enough to stream video full time).

A recent study showed that in some countries there are now more mobile phones in use than people - Germany has about 5 million more phones than people, but the UK is coming close to parity...

  bremner 10:25 13 Apr 2011


But if I were to count 11 digits instead of the 9 I have, then the total number of worldwide telephone numbers available would be 1000 billion not the 10 billion you suggested.

The number, however big is more than sufficient for every person and business to have as many landline and mobile numbers as they want.

And should the world populations become 10's of billions then they can make phone numbers 12 digits long but of course by then phones will have long since be relegated to museums :o)

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