OpenArc Systems Management started in 1991 and deals in banking and finance, securities and stock market and enterprise resource management solutions.
OpenArc chief Daya Hettiarachchi said its software was secure and complied with Sri Lanka's central bank guidelines and could be used by any bank, finance company or other firm.
Etisalat is the first mobile firm to sign up with Open Arc to use its 'SkyPay' branded mobile and internet banking platform, the firm said.
"At Etisalat we understand that a mobile telecommunication provider's role is changing," Etisalat chief executive Dumindra Ratnayaka said in a statement.
"Providing mobile phone connections alone was in the past, the future is about Telcos providing complete solutions to mobile population.
"That is what we are providing with our high speed Mobile Internet Connections and Mobile Banking is the next step in this paradigm.
"