Exclusive, the brislan case in the high court extended the meaning of 'other like services' in favour of the Cwth parliament
An exclusive power is a power which either by it's nature or by specific wording in the constitution is only within the jurisdiction of the Commonwealth parliament and thus the states are restricted from legislating in the area.
The power described in S51(V) is NOT an example of an exclusive power, as communication services aren't by their nature required to be legislated only by the federal government, and no other wording in the constitution states that communications services are only powers of the commonwealth.
Yes, the Brislan case extended the powers of the Cth parliament, however the case didn't necessarily make the states lose any powers, the states still have the power to legislate in areas related to S51(V), however if an inconsistency was to develop between state and commonwealth law, it is possible the high court would rule the inconsistent state law(s) to be invalid due to the conflict.
S51(V) is a concurrent power as both the state and federal parliaments can legislate in the area, HOWEVER should an inconsistency develop between laws of the two parliaments, following s109 of the constitution, the federal law would prevail to the extent of the inconsistency.
An example of an exclusive power would be, for example, citizenship and immigration, as by it's nature citizenship is granted at a federal level.