a method of communication or discussion that is not direct or made public

They were accused of paying a businessman to act as a secret backchannel to top officials. 他们被指控付钱给一名商人，让他充当与高层官员的秘密联络渠道。

to communicate or take part in discussions in a way that is not direct or made public

He was asked about his role in backchannelling between the two governments. 有人问他在两国政府私下交流的过程中起到了什么作用。