SLT 'i-Sri Lanka' project was started in 2011 to expand the telco's optical fibre network deploying fiber-to-the-node (FTTN) multi-service access nodes (MSANs) closer to customers.
"This reduces the length of the copper connection with a resultant significant increase in reliability, quality and broadband data speeds," SLT said in a statement.
"Reducing the copper cable lengths not only improves reliability, but will reduce maintenance and replacement costs.
"Through this programme SLT has already brought ultra high speed broadband connectivity at speeds of up to 20Mbps (megabits per second) for many of its fixed customers."
The first phase of the project, which has just been completed has added 40,000 new broadband circuits to the network.
"We are delivering against our strategy to evolve a world class broadband access network accessible to all Sri Lankans, to increase broadband penetration, which directly contributes to economic growth of the country," Greg Young, chief executive of SLT said in a statement.
Despite a global decline in fixed line access, SLT says it has increased its fixed customers by providing broadband.
SLT says by end 2011 there 844,000 broadband customers including mobile broadband.
SLT says over the next 18 months a capacity of 600,000 new broadband connections will be added to the network. Over next two years the firm says it is planning double its 300,000 broadband customer base.
At present about 50 percent of SLT's fixed access customers had 2Mbps access and could receive PeoTV, an IPTV service.
Young say the when the -Sri Lanka project is complete 90 percent of its fixed service will get 20Mbps access.
It also will also improve operational efficiency by reducing maintenance and operational costs, improving network reliability, he said.