On 24 June, 2015, Telegram published the Bot API, enabling machines to talk Telegram. From that day on, not only can human use Telegram, so can machines.
For those who don't know what Telegram is, it is a messaging app, very much like WhatsApp. This tutorial is going to teach how to send a Telegram message to your Raspberry Pi, and how to make your Pi telegram back.
Go to App Store (iPhone) or Play Store (Android), download and install Telegram on your phone.
Now, you can use Telegram. Not yet for the Raspberry Pi. Telegram reserves a special kind of accounts for machines, called bot accounts. As the owner of your own Pi, you have to obtain a bot account for it.