1What is Telegram Channels? The optimal dimension of the avatar on Telegram is 512px by 512px, and it’s recommended to use PNG format to deliver an unpixelated avatar. Private channels are only accessible to subscribers and don’t appear in public searches. To join a private channel, you need to receive a link from the owner (administrator). A private channel is an excellent solution for companies and teams. You can also use this type of channel to write down personal notes, reflections, etc. By the way, you can make your private channel public at any moment. How to Create a Private or Public Channel on Telegram?