To make these actions happen, you need an application to sit in the middle of the call, act as a back-to-back user agent, and provide access to the services mentioned.

要实现这些操作，需要有一个应用程序在呼叫的中间位置充当背靠背的用户代理，并提供对上述服务的访问。

youdao

The refusal to sit down in a relaxed posture when in the presence of those not trusted. Hair up at the back of the neck, and not wanting the enemy to one's back.

当在不信任的人面前时拒绝坐下来处在一个放松的姿势中，脖子后面头发竖起，还有不想让敌人在你后面。

youdao

And so he never done nothing for three months but sit in his back yard and teach that frog to jump.

VOA: special.2009.08.29

If any of you don't want your image recorded and posted on the web, you're supposed to sit in the back three rows.

如果你们中的任何一位,不希望被拍摄下来并被放到网络上，你们可以坐到后面三排去。

麻省理工公开课 - 计算机科学及编程导论课程节选

He jumped from table to table, eating standing up--he didn't like to sit down very much, his back hurt--; or walking around.

在不同的桌子间窜来窜去,站着吃东西,他不怎么喜欢坐着,因为长年背痛,或者在宴席间四处走动

耶鲁公开课 - 欧洲文明课程节选

It's also good for Ryan to sit back and to learn from other people - he's had to try to teach himself at Gloucester and that's been the hardest thing.

BBC: Exiles 'fresh start' excites Lamb

In that discrepancy is probably a place for you to sit back and listen to yourself.

FORBES: Why I Said No To Venture Capital

Then, I got to sit back and listen to them all brainstorm and debate until I had some long-term goals, structure for how to reach those goals and what I wanted most of all, a to-do list.

FORBES: Living On The Edge