It's a call from someone using a free IP/web based phone service. It could be a scammer, or someone you know. For me, it turns out to be my nephew who just wanted to say "Hi". He uses an iPod or iPad.
Just received a call from this number and he said he was from a shpping dept. holding a shipment. When I asked what it was he hung up. Sounds sketchy !
This guy called with accent saying I have complaint. I had ask him twice what he is taking about. Time to time we get prank calls; so it it didn't take me long to figure this out. He wanted compensation!! I asked him why? He said we don't specific item in our establishment and wants to give him Gift Certificate. So I told him to stop by at our store to talk about it (just to be polite). And hung-up on him saying, "Thanking for calling".