SMS only 160 characters

Why is the limit of an SMS 160 characters?

It’s not a decimal number ie. not a multiple of 10 and has nothing to do with dozens (12), not even a butcher's dozen. So why is there a limit of 160? BTW if you often push the limit of 160 characters, then you really need to get a life. But, back to basics … why the limit of 160?

There are 2 stories and reasons suggested.

A man called Friedhelm Hillebrand, Chairman of the Global System for Mobile Communications (GSM), had the task of setting the limit on the amount of characters a text message could contain. This would become the international standard.
He did this by analysing typical sentences viz. questions and answers. He also reviewed messages written on postcards and received by Telex transmissions. (Telex was not so long ago the state of the art message transmission technology.)

Friedhelm Hillebrand arrived at the answer of 160 characters. His recommendation became the standard.

The second story and a more technical consideration related to the size of packets transmitted via the GSM (mobile phone) network. The packet size is 140 bytes and with a bit of technical ‘compression’ this equated to a text message limit of 160 characters.

Who knows where the truth lies. Perhaps the technical answer (of 160) was tested by Friedhelm’s research into written messages.