Called back and just get engaged tone

It was an automated answering service telling me that i won something, i just hung up on it. only registration details i can pull on this number are:
suburb: Exhibition No2,Exhibition B Isdn

called me on 20/2/2008 saying I won a $50 sports pack then asked me to press six to play some quiz

Called me on my mobile telling me that I won something ($60). Don't know what happenned.

It was an automated answering service telling me that i won something, i just hung up on it. only registration details i can pull on this number are: suburb: Exhibition No2,Exhibition B Isdn

called me several times re: a competiion not good .