ℹ️ How to add a secondary account from the Test DC (Data Center)

• TDesktop Beta 2.1.14+ and Unigram (NEW)
  Press Alt+Shift and right click on Add Account button, there will be a context menu > Test Server

• Telegram Mac
  Open Developer menu (5 clicks on the Settings icon) > press Command and click on Add Account > Login

• Telegram iOS
  Open Debug menu (10 taps on the Settings icon) > Accounts > Login to another account > Test

• Telegram Android Beta
  Go to Settings > scroll to the bottom > Switch Backend > Login.
WARNING: You will need to relogin when back to the Production Server by click again on Switch Backend.
(Update: Switch Backend was removed on v6.3-7.1, it’s back on v7.2)

Notes:
  Test DC is a Test/Beta Server for Developers to test something.
Sometimes new features are deployed there first, so new updates can be tested without affecting the Production Server.