Googles stock dialer for Android is the Phone app and it gets updated regularly via the Play Store. In February, it was updated to support Google transcriptions on voicemails for T-Mobile customers. Also, the Phone app was updated to integrate Duo video calls by Google, directly from the dialer.
Today, Google is releasing the Phone app on its Beta channel, offering anyone a chance to check out new features before they roll out to everyone. According to Android Police, Google does not recommend that you sign up for the Beta using a Google account that is tied to your main smartphone.
There is currently no notable difference between the Beta and stable releases of the app, though it will likely change over the next few days.
Via Phone app Beta