I called back number (02) 7201 9674 rang once then gets disconnected automatically.

Called me twice - I didn't answer. Assuming its a scam

When I answered and said hello, there was no reply and then they hung up after about 10 seconds

Rang my home at 7.38pm on a Friday night and hung up when answering machine cut in. On numerous call back attempts, at all times of the day and night, the line is constantly engaged, Obviously up to no good!