This is maybe a little bit off topic, but where can you actually enroll in e-channel? I live in Chengdu and when I asked someone the last time I was leaving CTU I was told only Chinese passports can use the e-channel, which obviously isn't true. However, there is no need to enroll in anything for Chinese people to be able to use the e-channel, so do only certain airports have the capability to enroll foreigners?

I tried to look around a bit but I didn't want to look too lost/suspicious in an immigration area.