i had a missing call from this number and I heard a woman voice with some dirty talk when I call back. I think it is taped, because she didn't answer a [***] I said.(TAIWAN)
I don't think you should pick it up I have read other posts about there calls and it seems to be a fraud. You may be charged for no reason and they may be able to copy down everything on your phone. I may not be correct but at least this is what I read. You shouldn't report it to the police because this is a minor matter. If they harass you many times in a day or you are charged for nothing, then you should go and report. In the meantime, don't pick up any international calls unless it's those that you recognise. And do not be tempted to answer or confront them, in case you get charged (for telephone bills).