Who called from +65 9422 8123?

I just received a phone call from +6594228123 which I did not answer at first when I suspected it to be a spam call. So immediately I used my office phone to call the said no. and found it was an engaged tone. I then answer the call, but it came on a message: "The ministry of health informed you......." I immediately put down the phone as we it doesn't sound like its an official called. I immediately called the same number from my office phone again to check if it is a valid call. The phone rings with a Singapore tone and I waited if someone would pick up the call, but no one answered until the ringing tone lapsed. I tried again another time but again its the same.