Simmons & Simmons is networking its offices in London, Paris, Brussels, New York and Hong Kong, linking over 1,250 employees through a common desktop platform.
It is thought to be the first law firm to use an international frame relay service so extensively worldwide.
The service, which will interconnect local area networks, is designed to support all the firm's email and file transfer applications. It should also be able to cope with global database queries.
Chris Roberts, director of information technology at Simmons & Simmons, said: "The decision to implement international frame relay underlines our commitment to be at the forefront of technology and underpins our reputation as a truly global law firm."
The contract to implement and manage the international relay service was awarded to Mercury Communications.