I heard this in a conference call.

Problem:
The adverb “back” in “echo back” is redundant.

Explanation:
The verb ” echo ” means to return a signal or message, so the meaning of “echo back” would be to return back [sic] a signal or message.

The “re” in “return” means back. Therefore, one could argue that something that “echoes back” would never reach the original sender.

Solution:
“echo”