The latest Telegram update has added A.I.-powered voice calls to the application for users in Europe, and although the feature is not yet available globally it should be rolling out to users around the rest of the world where Telegram is available very soon, so it won't be too long before Voice Calls is a feature that all users can get their hands on. That being said, there is no explanation of how long "very soon" is so if you use Telegram it's best just to keep an eye out for the update.
Like the messages portion of Telegram the all-new voice calls feature is built to offer a secure way to connect and talk to others. Security for the calls was a big part of offering the feature to users, and it uses the same end-to-end encryption that you'll find with the messages. However, Telegram has switched things up just a little bit by changing the way two users verify that the call is secure, and instead of using the same key exchange verification that is uses for messages, the app simply verifies that calls are secure by showing a set of four emoji on screen, and if they match for both parties on the call than the voice call is secure. Telegram says that this was an easier method for the verification process which is the reason for adding the improvement.
It isn't all about security though. Telegram also wanted voice calls to be fast and they wanted users to have plenty of granular control over the feature, which is why they made it so that calls will first try to connect two people on a call using a peer-to-peer connection, and if they can't reach a p2p than the call will fall back to a connection on the closest server. As for control, the user is able to configure who is able to call them through the app, and if they'd rather not receive calls from anyone they can turn calls off completely. Voice calls are also powered by artificial intelligence that will learn from each call a user makes, analyzing things like network speed and ping times to help improve future calls so that they deliver even better quality than before. When the feature rolls out to your device, Android users can find the calls feature in the hamburger menu.