Short pre-history.
Phones have been a huge part of people's life in 20’Th and 21'st centuries, however, how did people communicate before the phone? The answer is, the telegraph. It is very similar to what instant messaging is today, however it had lots of wires, and was not at all instant. Not only that, but it was also large, a lot larger then a cell phone is today, but worse of all, it could only transfer one message (in this case, letter) at a time, so instead of getting the entire message in a matter of seconds, you would get only one word per second. This was obviously very uncomfortable, however it was good enough for the time being, for it held it’s legacy for about 30 years, until Alexander Graham Bell invented a device that could not only transfer more then one message at a time, but human voice itself. Thus, the telephones appeared, and the idea of instant messaging disappeared for a long time, until the cell phones were created, and instant messaging (or SMS) swept entire generation, and made people forget about the fact that phones are actually used for calling someone, not texting in classes.