How Does Texting Work?

Geek Level: MEDIUM HIGH. 

Texting -- SMS; Short Message (or Messaging) Service -- has got to be one of the most intensively used communication modalities. 

Via Android Authority -- 

What is SMS and how does it work?

by Robert Triggs on October 13, 2013

We’re all familiar with SMS messages, after all it’s one of the oldest and most commonly used methods of mobile communication. But there’s a surprising amount of co-ordination and technology working in the background to send such seemingly simple messages. So let’s take a look at how it all works.

For a start – SMS stands for short messaging service, a protocol used for sending short messages over wireless networks. Unlike many services in use today, such as MMS and other data driven services, SMS still works on the fundamental voice network, and is based on the big three GSM, CDMA and TDMA network technologies, making it a universal service.

SMS allows for text messages of 160 characters (letters, numbers and symbols) in length. Or for other alphabets, such as Chinese or Arabic, the maximum message size is limited to just 70 characters. Part of the reason for this is that SMS messaging was original considered as an afterthought added on to the spare bandwidth available on wireless voice networks. There was always a limit on how large these messages could be, hence why certain characters, such as foreign alphabets or obscure letters, still take up multiple spaces of the 160 allowance.

The 160 limit was eventually decided upon by Friedhelm Hillebrand, who observed and tested the typical number of characters in the average sentence, combined with a compromise on the available bandwidth at the time. Nowadays bandwidth isn’t so much of a concern, and messages can easily be sent back to back and recompiled on the receiving handset. The, now considered, low-bandwidth requirements of transmitting these short alphanumeric strings allows for worldwide messaging with very low latency.

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