By default, Jabber will use your webcam when you place or receive a call if one is available. Here is how to change the setting to start calls without video:

1.  When in Jabber, click on the 'Menu' icon (located in the upper RH corner of the Jabber window).

2.  From the drop-down menu shown, select 'Settings'

3.  From the 'Settings' window shown, on the LH side of the window select the 'Calls' option.

4.  From the 'Settings' window after 'Calls' has been selected, look in the upper portion of the window under the 'Calls' header.  There are two options shown.  They are:  'Always start calls with video' and 'Never start calls with video'.  To disable your webcam in Jabber, make sure the 'Never start calls with video' option is selected.  Then, first click the 'Apply' button on the bottom of the window, followed by the 'OK' button to save your settings and close the 'Settings' window.

5.  You may want to sign out of Jabber, and then sign in again to ensure the video changes are set in Jabber.  Once complete, when either placing or receiving a call in Jabber, you will only hear audio.