Optus the second biggest telecommunications provider in Australia will start providing 4G mobile services next year as it will also begin 4G services on a new spectrum previously used by analog television.

Chief executive Paul O' Sullivan announced in Sydney today that Optus will start offering its customers 4G mobile services starting in April 2012 in Newcastle with plans to expand to Sydney, Melbourne and Perth later that year.

The company will also upgrade its 3G mobile network after customer complaints about slow internet speed. Optus will start scaling back on its 2G network and use the freed up radio spectrum to beef up its 3G network. The telecom company promised a boost to 3G capacity in Sydney, Melbourne and Perth this month with other cities getting the upgrade in the next few months.

"Optus has invested nearly $2 billion in the past four years and we will spend over $500 million in this financial year alone on our mobile network," O'Sullivan said.

As for the 4G network Optus will start installing 4G in Perth, Sydney and Melbourne next month. It will also be the first carrier in the country to use radio frequency previously used by analog TV.

Optus will begin testing 4G over TV frequencies in Bendigo, Victoria. The 700 MHz frequency will ensure that the signals will travel far and get good coverage inside buildings. Theoretically an LTE technology has maximum speeds of 100Mb/s and in real life tests it provides 40 to 50 Mb/s with upload speeds of 20Mb/s, making it faster the wired ADSL2+ and cable.