How can I create a video calling test service for my users?

Sometimes, especially with the first call, there can appear problems, maybe the browser is not supported, the user’s microphone is muted, and so on. Or maybe the user just wants to check how they look/sound in the call.

I would love to offer my users the possibility to test a call without having to call a real person. Similar to the “Echo / Sound Test Service” from Skype.

Can you offer some suggestions on how to do this?