Who called from 2019843969

I got a call from this number at 9:40 at night, once I answered they hung up.  My husband leaves for work at 3:00 am so needless to say neither one of us are happy about this.  My called ID states it is DELTATHREE INC, (telemarketer I assume) when I called back I get the party you are trying to reach is currently unavailable.

I have no Idea who/what Deltathree Inc is, but they called me at 9:37pm.

Delta Three, Inc. is now using 201-548-2048 and calls with no message or reason.

They hang up after saying hello and you say hello.

What is this company?