The investment bank has also cut costs and simplified system management following the installation of a converged voice and data IP network across its offices worldwide.
Using the follow-the-sun system, users can dial their country office at any time. Out of hours they are transferred automatically to a centre working office hours in another time zone, which then deals with their query.
Putting voice and data onto one network has allowed Barclays Global Investors to put data and voice groups under one manager and simplify the management of the network.
Patricia Green, telecoms manager for Barclays Global Investors, said, "We have eliminated trunks and associated plant. Where there were dedicated resources we will make savings. Having only one network to administer obviously simplifies things and installing phones is so much easier [using Dynamic Host Configuration Protocol, which automatically assigns IP addresses to clients]."
With thousands of clients moving funds worth $800bn (£544bn) through its networks every year, the company puts a premium on reliability, performance and cost effectiveness in its communications.
Green said Barclays Global Investors is "on the leading edge" and that most financial services firms are not using Voice over IP. She said the company's aim is to develop solutions that other financial services companies want.
In selecting its IT suppliers Barclays Global Investors organised a seminar for several candidates where it presented its specifications and asked, "How can you satisfy our requirements?"
Avaya was chosen for its Definity communications servers.