Not necessarily, if they are running EEA or EVM. This is an addon for ESF and you'll have to go get that to play on those servers. Try to avoid servers with EEA or EVM in their name if you don't have it. Sometimes you'll still have to download sounds and such, this is because they are running some type of plugin, in which you need sounds. So if it is an EEA or EVM server, don't join it, if it isn't, just wait and download the sounds. Oh and no starting threads about how to install\where can I get one of these addons. You can get the information
here. Any thread you create about EEA or EVM is going to be closed, so keep any questions you have about their addon, on their forums. Hope this helps.