Usernames and t.me
Official telegram.org Source
Once you've set a username, you can give people at.me/usernameor ausername.t.melink. Opening either of those links on their phone will automatically fire up their Telegram app and open a chat with you. You can share username links with friends, write them on business cards or put them up on your website.
This way people can contact you on Telegram without knowing your phone number.
If you don’t want to set up a public username and don’t mind sharing your number, you can also create a t.me linkwith your phone numberininternational format– for example,t.me/+123456789. This type of link can quickly open a chat with you from any app, however, it will only work if yourprivacy settingslet others find you by your phone number.
Official Telegram Reference: https://telegram.org/faq
Part of the TGWAY.com Official Telegram Knowledge Base (98 Verified Q&As).