Are we going to have a shortage of telephone numbers?

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

04 September 2022

It’s hard to imagine that there was a time when one telephone line served many people – in most cases more than five. In the year 2001, when the first independent mobile phone company (Kencell) started operations in Kenya, there were just 300,000 land line connections in the country serving a population of about 33 million people. That is, one line for every 110 people!

Today, the situation is inverted: there are more telephone lines (64 million) than people (54 million)! The reason is that there are very many of us who have more than one line – I have 2 that I use regularly.

Now, our telephone numbering system comprises of 9 unique digits: three in the prefix and six identifying the subscriber. The leading zero is redundant these days. It was necessary in the old days of town code numbers; it signalled to the exchange that you the next number you dial will be a town code.

The question that many people keep asking me is how many lines can fit in one prefix, say, 0722? Well, the answer is from 000000 to 999999; that is one million exactly! If you don’t believe me, count them!

In the early days of mobile telephony, the prefix used to identify the service provider; Kencell was 073X and Safaricom was 072X. However, with the introduction of number portability across networks, this is no longer the case. Indeed, one of my two lines starts with 0733 yet it is on Safaricom!

So, we can extend the question and ask: how many lines can be accommodated in the 9 digits (including the prefix)? The answer is 10 billion exactly – assuming that 000000000 is available. Therefore, we have no reason to worry about a shortage of telephone numbers any time in the future.

In related news, MPESA codes comprise of 10 characters – letters and numbers. Currently, the system handles about 20 billion transactions per year. So, how long will it take till they run out of codes?

Each space in the code can take 36 characters (0 to 9 and A to Z). This makes a total of 36 x 36 x…...x 36 (ten times). That comes to 3.66 quadrillion possibilities! If you’ve forgotten, one quadrillion is a number with 15 zeroes.

Dividing 3.66 quadrillion codes by 20 billion transactions per year gives 1.83 million years! In short, the codes will never get finished. If you doubt the result, do it in your calculator!