call sb. back

He never calls me back

回电给某人

他从不给我回电。

get back to sb.

You need to get back to me quickly on this.

稍后再联络某人

你一会得快速联系我。

get through to sb，

I always find it hard to get through to him.

He never answers his phone.

联络上某人

我发现总是很难联系上他，他从不回电。