<extension name="call_extension">
<condition field="network_addr" expression="10.1.1.1">
<action application="set" data="continue_on_fail=USER_BUSY"/>
<action application="set" data="hangup_after_bridge=true"/>
<action application="bridge" data="sofia/gateway/profile/${sip_to_user}"/>
<action application="transfer" data="header_test_extension"/>
</condition>
<extension name="header_test_extension">
<condition field="${sip_h_X-Header-Name}" expression="Header Value">
<action application="respond" data="404"/>
<action application="hangup"/>
</condition>
</extension>
That's the idea, but I am really not sure you can test the value of ${sip_h_X-Header-Name} if that header is sent back by the called endpoint...