Optus has switched on LTE-Advanced Carrier Aggregation for 4G customers in Sydney, Melbourne, Brisbane and Adelaide. That means potentially faster data speeds -- but only if you have a phone that can take advantage of it.
Carrier aggregation involves combining multiple channels on 2300MHz spectrum for higher speeds. Theoretically, downloads could hit 200Mbps, though you're very unlikely to hit that in practice. Optus says its trials, which have been running since December last year, have typically seen a doubling in speed.
To access the aggregated service, you'll require a compatible handset or hotspot that supports aggregation. Optus says it will soon be selling devices but hasn't released details (we've asked for more information and will update when we hear).
Optus says the service will also be extended to Canberra "within weeks". Telstra already has a carrier aggregation wi-fi modem in market for its network in a number of locations, and says it will be offering aggregation more broadly in 2015.