Go to Options > Calls and turn on Mute audio by default for Jabber calls. The Calls tab is only available if you have set up Phone Services in your Accounts tab.

Go to Preferences > Calls and turn on Mute audio by default for Jabber calls. The Calls tab is only available if you have set up Phone Services in your Accounts tab.

Go to Settings > Call Options and tap Auto Mute under Mute me on all Jabber calls. The Calls tab is only available if you have set up Phone Services in your Accounts tab.