The Webphone is supported on the following web browsers:

Firefox limitations

Setting up different audio devices doesn’t work in Firefox unless a specific flag in the Firefox configuration settings is turned on. To do this, type “about:config” in the search bar. You will receive a warning, and when you continue, search for “setsinkid”. There should be one visible rule with the name “media.setsinkid:enabled”. Double click on the rule to turn the flag on.
Selecting of an audio device as a headset does not work for phone call audio. Unfortunately at the moment Firefox can only play the conversation audio on the device that is set up as the default device on your computer. If you want the change the default device you need to do it in your operating system settings.