[The Economist]: Use of DPI for Internet Censorship

"Belarus, Ethiopia, Iran and many others are believed to use “deep packet inspection” to look into internet users’ communications for subversive content, aided by hardware from, among others, China’s Huawei and ZTE. Obligingly, internet users who know they are being watched are more likely to exercise self-censorship in the first place".

See "Internet controls in other countries" - here.