Telegram Basics
Official telegram.org Source
You can write to people who are in your phone contacts and have Telegram. Another way of contacting people is to type their Telegramusernameinto the search field – you don't need to know their phone number to do this.
Official Telegram Reference: https://telegram.org/faq
Part of the TGWAY.com Official Telegram Knowledge Base (98 Verified Q&As).