通常在以下的情况中碰到
1.你打电话找人,人家忙,于是说:let me get back to you ( a bit later).
2.你写信,特别是mail,又是紧急的,收件人手头来不及处理你的急事,那他也会说:I will be back with you later on,I will come back to you later,I will get back to you later.
打架的时候,你打不过人家,按照天津人的习惯,"回家喊二哥来帮忙"时,你也可以恶狠狠的说:I will get back to you soonest.
正如你说的,"看来翻译一定要看上下文的意思啊".