If you are referring to thins like Battleping and the likes, here's what someone has written in a forum that seems to make sense, i suppose the same holds true for South America. The relevant info is "SSH tunnel"
The advent of proxy tunnels came from the demand of Oceanic WoW players. Incase you don't know, the backbone connecting Oceania to America is a huge piece of shit and once you leave Australia/New Zealand packets gain an extra 200ms because gaming packets get shaped leaving our country, and then they get shaped going into America. Generally you can ping about 200~ to US Servers, but in real-time the game data will end up getting prioritized to hell and back and you'll have a latency of around 500.
The way Lowerping, Battleping and Smoothping etc all work are by establishing an SSH tunnel to a proxy in America and sending the SC2/WoW data through it. SSH traffic has much higher priority than gaming traffic does, so instead of being delayed, the data flies through. Afaik, it also doesn't get shaped as incoming traffic from the Blizzard serverside, because they're originating from a proxy inside of the US.
Feel free to correct me, I might be wrong on some things, but that's what I've picked up from using the very first tunneling service (Lowerping) since it came out