Misc. Dialplan Tools delay echo
From FreeSWITCH Wiki
Places the calling channel in delayed loopback mode.
It simply returns everything sent, including voice, DTMF, etc but with the specified delay [ms].
It is generally useful for checking if RTP audio path works both ways. Normal echo app can fail when tested on speaker phone.
From the Dialplan
<action application="delay_echo" data="1000"/>