Google today introduced a new feature called "Hold for Me" that does the waiting in your place while your call is on hold. The capability was announced along with today's unveiling of the Pixel 5 and Pixel 4a (5G).
With the new feature, Google Assistant will stay on the line for you so you can do other important tasks while waiting for a business representative, for example, to return to the call. It is available in an early preview on the Pixel 5 and Pixel 4a (5G) in the U.S..
The new capability applies only to calls made to a toll-free number, though. It uses Google's Duplex technology to identify a hold music and distinguish the difference between a recorded message and an actual person speaking. When someone on the other line is ready to talk, Assistant will then send you a sound alert, vibrate your phone, and display a prompt on your screen.
To protect your privacy, audio is processed only on your device and it works even without an internet connection. Google says it won't save audio recordings to your account unless you choose otherwise to help improve the capability. Nonetheless, it completely stops processing audio when you return to the line.
You can enable the feature by opening the Phone app, tapping on the three-dot menu, and going to the settings section. From there, you can turn on the Hold for Me option. Keep in mind that you must also turn on the feature with each call before Assistant waits on hold for you.