I received a call from this number, when I answered there was no one there and then it disconnected. I tried to call back several times but the call never went through and disconnected (timed out).

I think it is GFC Investments. I partly signed up for a bitcoin trading thing (just being curious) from an ad on Facebook which went to a news article about Kochi (Australian Newspaper ad) endorsing this Bitcoin thing but I did not go any further with it as later I noticed that the website address was not what was being promoted and if you clicked on the links in the page they all went to this bitcoin promotion. I then continued to be called by them trying to sign me up!

I also received calls from (03) 8376 2098, (02) 6145 0861, (02) 8311 6608 for the same place.

I called back number (02) 6145 0860 rang once then gets disconnected automatically.

Had over 30 calls from this number and numerous other numbers, they keep asking for someone else have been told repeatedly that they have the wrong number and to take my number of their records but I still get more calls asking for the same person. Borderline harrassment the number of calls from this call centre.