What does Unlock (Activate) do on DegenPhone?

It's free, and you do it once, in My Numbers. After that, SMS from any app or person arrive in your chat with @DegenPhoneTonBot. When the bot says "Activate", it means this button. The button says "Unlock Number and view messages".

You can't undo activation. The number is marked Recycled and can never become Fresh again. Recycled numbers usually sell for less. So activate when you need a code, not before.