Some people used ICQ, some AIM, some Yahoo. Some IRC. And so it is today. At work and in private context.
I feel we have come full circle in the 20 or so years.
Now I have Signal, WhatsApp, Telegram, FB Messenger, Slack, SMS, Google Hangouts, MS Teams on my mobile phone.
Not to forget that some use Instagram and some LinkedIn to communicate.
Nowadays I need to have a mapping table of whom to contact via which channel/app.