The call HOLD (HOLD) supplementary service, allows a user to interrupt communications on an existing call and then subsequently, if desired, re-establish communications.

呼叫保持补充业务能允许一个用户中断一个已经存在的呼叫的通信，随后在要求时仍可重建通信。

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Service is busy now, please hold on and your call will be answered in approximate 5 minutes.

现在服务正忙，请不要挂机，我们将在五分钟接听您的电话。

youdao

From my experience, there are a few good ways to do that: make online self-service links prominent on your website and always offer them anywhere you provide your customer support number, integrate online help throughout key processes, promote Web and self-service resources in telephone hold messages, let call center agents notify customers of self-service options, and reply to email questions with the link to self-service content to re-enforce self-service availability.

FORBES: Eight Steps To Great Customer Experience (Part 1)