hi Ali,

this is how eavesdrop works, the arrow points to the direction of the audio flow, in this way C could listen but no talk:
           C
           ^
           |
           |
A<----->o<----->B

this is how three_way works, C could listen and talk to A and B, just like in a conference:
           C
           ^
           |
           |
           v
A<----->o<----->B

Usage:
<action application="three_way" data="<uuid of a bridged call(A<->B)>"/>