We always recommend testing your audio and web cam devices before joining actual calls.

Test your audio device

Click on your profile icon at the top right of your Teams window, then click Settings.
A Settings pop-up window will appear. On the left, navigate to Devices. From there, you can click the Make a test call button to test your audio settings.

Test your web cam

We'll use the below steps to preview your video feed before joining a call.

Navigate to your Calendar, then click Meet Now. You can click this button at any time to create an instant meeting in your own Teams meeting room, then invite multiple participants. But in this case, we'll be using it to test our meeting call/video settings.
Before you join your meeting, you can turn on/off your video feed, blur your background or change it (or even add a new custom background), turn on/off your audio feed, and change which device you join the meeting with. We recommend playing around with these settings before joining a real call so you can familiarize yourself with the options available.
1. When using the custom backgrounds, just note that they work better with more contrast, so if you stand out well from your background, it should work fine. It does also use a lot of your computer's resources, so if you experience lag, try turning off custom backgrounds, and even consider turning off your video feeds.

If you have any questions or want us to help you test out your devices, please open a ticket with the Help Desk.