How to address the listener when you do not know his or her name or title?

Question

How do you address the listener when you do not know his or her name or title? There are the 2nd person pronouns 너 and 당신, but those are generally either rude or awkward in most situations. I know that usually 2nd person subjects are just omitted, and this works fine it most situations, but occasionally, I really just want to say "you" to describe who I'm talking about. It generally works out fine with a simple hand gesture pointing to the listener, but I'm curious what would be done if, say, it was a telephone conversation and nonverbal communication wouldn't work, or other verbal alternatives in face-to-face conversations.

This used to really bother me when first learning Korean. Books teach a bunch of ways to say, "you" and then tell the learner, "but don't actually use any of them in an actual conversation." I haven't actually run into this problem recently, so I've apparently gotten used to it and/or coped with other techniques, but asking because I'm sure others have run into this same problem, and I'd still like to know more alternatives.

To be clear, I am looking for ways of address when you do not know the listener's name or title, so things like name + 씨 or title + 님 are not what I am looking for.

Answer 1

On the Internet, when we want to address anyone whom we don't know, we use 님.

For daily life conversation,

There are other expressions you may use, such as 아저씨, 아줌마/아주머니, 할아버지, 할머니. If talking to a younger person, you can use 누나, 언니, 형, 오빠 if you want a closer relationship. Otherwise, you may use 그쪽.

If there is more than one guy,

Easy, you may use 여러분.

Answer 2

I think this question is hard to answer, because I think we(Koreans) always care about the relationship between the listener and ourselves.

What happens when the listener says, "누구요?" and you need to clarify?

Say we're talking on the phone. I would always try (maybe unconsciously) to figure out the relationship between the listener and myself. Is the listener's voice is that of an elder, or a kid or about same age? Man or woman? Am I in a situation that I'm going to ask for help or I want to hear some apologies?

After considering all of those I would choose an apropriate word from the list mentioned by others in the comments. You may notice that most of those words are used to name family members. This way of using family names is not found in English, and it can be described as a culture of Koreans.