It sounds like one of those scams where they call and hang up, hoping the person they called will be curious enough about who they were and what they wanted so that they will call back. Once the connection is made they harvest and copy information from the person's phone (such as their bank account, passwords or sim card number) or charge exorbitant rates for returning their call.
I would advise calling your network provider and let them know that you responded to a possible scam caller and ask them what can be done about it. If the scammer called your smartphone, go into your Google Play or App Market app and download a call-blocker. I have an Android phone and use the Mr. Number app. It's free and works very well.
Never feel obligated to answer a call from a number you don't recognise. Wait for the phone to stop ringing without responding in any way then Google the number. If there are complaints listed against the caller then you know what to do.
Have a good day. I hope this helped.