Optus has won an AU$530 million, five-year contract with ANZ Bank to supply telecommunications and managed services to the banking giant.
Optus has held the contract with ANZ since 2009, but that original agreement was due to expire in 2014.
Optus will supply domestic and international data network services, mobile services, contact centre services, and management services to ANZ across 32 countries and the bank's 48,000 employees.
ANZ CEO Mike Smith said that the deal is the largest managed services agreement ever signed by ANZ.
"The services provided by SingTel and Optus Business underpin the connectivity of our business and the delivery of services to our customers in Australia, Asia, and the Pacific," he said in a statement.
"This agreement represents ANZ's largest managed services relationship, and we are very pleased to continue our partnership with SingTel for a further five years."
The bank is making steady progress on its AU$1.5 billion Banking on Australia tech transformation program. In April, the bank reported that it had rolled out 43 Cisco video conferencing systems into bank branches and 800 NCR iATMs.