Here's one for an ATC type person...
AIP GEN 3.4 4.14.3
(ATC callsigns)
The name of the location or the service may be omitted provided that satisfactory communication has been established.
I would take this to mean that once you have made an initial contact,
(eg Sunshine Coast Tower, ABC, Maintaining 2 thousand 5 hundred
ABC, Sunshine Coast Tower, descend to 1 thousand 5 hundred
Descend to 1 thousand 5 hundred, ABC)
{No, it's not a complete example, I know...},
Every subsequent contact should begin with either Sunshine Coast or Tower?
(eg Tower, ABC maintaining 1 thousand 5 hundred
ABC, Tower.)