Echo, designated CT-1409, was a clone trooper who fought during the Clone Wars. Originally identified as CT-21-0408, he belonged to the Cadet unit Domino Squad during his training days, and though he barely made it out in to the field, he became a high ranking member of the 501st Legion. He was given the nickname "Echo" because of his tendency to repeat orders, and always had a strong passion of reaching the rank of ARC Trooper, which he eventually did. He fought many times with his only remaining squadmate, Fives. 

As a cadet, Echo was a member of the disfunctional Domino Squad who always told the other members of the squad that they had to follow orders and always repeated orders from command, earning him his nickname. Echo however began to work well with his squad durring the re-take of their final test and helped them succeed.

As a rookie, Echo was able to deal with the ennui of the Rishi Moon outpost better than some of the other rookies. When the attack on the station came, he tried to help shut off the all clear signal, knowing that Kamino was in danger of being invaded, showing his care for his home planet and his clone brothers; examples being his sadness over Hevy and 99's deaths and helping to protect Kamino since it was his homeplanet and so many of his clone brothers were there.

He should sound like Dee Bradley  Baker, who voiced all of the clone troopers in Star Wars: The Clone Wars.