Dialog's service is based on frequency division - long term evolution standard (FD-LTE) technology requiring paired bandwidth for separate uplink and downlink channels.
Dialog last week bought 10MegaHerts of paired spectrum or 20MHz of raw bandwidth in an 1800MHz band auction from the regulator for 3.2 billion rupees allowing it to launch the service.
"It is indeed an honour and privilege to lead Sri Lanka’s mobile industry in to the 4G era with the launch of Dialog’s 4G Mobile service in the city of Colombo," group chief executive Hans Wijayasuriya said.
"The progressive spectrum management policies of the Telecommunications Regulatory Commission of Sri Lanka has once again ensured that Sri Lankan consumers will enjoy the region’s most advanced suite of Mobile, Fixed and Nomadic 4G LTE Services."
Dialog's fixed access unit, Dialog Broadband Networks, launched fixed fourth generation services in December 2012 using time division - long term evolution (TD-LTE) which originally evolved in China and does not require paired bandwidth.
Dialog said its 4G mobile services will deliver peak data speeds of 50Megabits per second on FD-LTE 1800MHz band 3 compatible mobile devices.
These included Samsung Note II LTE – GT-N7105, Samsung SIII – LTE, LG Optimus LTE, Sony Xperia V LTE and the Huawei Ascend P1 LTE and the Huawei E398U dongle.
Dialog said it will sell the dongle at 16,000 rupees and will also offer Huawei E3276S dongle later in April.
"Dialog will continue to invest aggressively in building a world class portfolio of Broadband Services for our customers based on Mobile and Fixed LTE, 3G HSPA+, Wi-Fi and Fibre Optic Connectivity," Wijayasuriya said.
"We are singularly committed to supporting the Government of Sri Lanka in its vision of empowering all Sri Lankan citizens with broadband connectivity, and accordingly we will ensure that our broadband services are available across Sri Lanka and affordable to all."
Director general of Sri Lanka's telecommunications regulatory commission Anusha Pelpita told LBO last week that spectrum had been kept affordable to allow cheaper services and spectrum sharing had also been allowed.
Dialog operates Sri Lanka's largest mobile service with 7.8 million subscribers.