Recently, Twitch gave creators the ability to add more security to their channels and chat to help prevent hate raids. The added security includes giving creators the ability to require phone verification for viewers who want to chat while they're live – a much needed step that is long overdue.
This setting is disabled by default (which is no surprise) but many streamers will likely start to turn this on to maintain high quality, safe streams for all kinds of community members.
If you haven't added your phone number to your Twitch account, you'll want to head to your Profile Settings and Security page.
Under the Contact section, there will be an option to add your phone number. Once you add your phone number, you'll get a text message from Twitch with a verification number to link it to your account.
And that's pretty much it! It's easy to do, and worth doing for that added extra layer of security while you watch streamers.