Hi this number is a Vodafone Australia number from where staff can call you and the number show up on your phone However it can not be dialled back to, so you can not call back to the person or department who called you. My advice their website tells the names of all of the executive team, you can email them in the format john.doe @ vodafone.com.au if you need to try and get something resolved.

I called back number (02) 9015 6000 rang once then gets disconnected automatically.

Caller: Internal Skype missed call

don't bother calling back you'll just get an engaged tone

Its is an internal forwarding number for skype missed calls

I called back number (02) 9015 6000 rang 2 times then goes to busy tone.