Markel will buy a news telephony system to cut call costs.
Communications company BIS is to supply Markel International with its Voice Service, which connects to the public phone system through a private IP (internet protocol) network.
BIS said that it aims to connect as many London Market organisations as possible in order to provide the community with free telephone calls.
The service allows customers on the BIS network to call each other free and permits discounted rates for calls made from outside the network.
Markel network manager Nigel Poll commented: "Markel International constantly strives to improve its IT services while reducing operating costs."
BIS clients include Lloyd's, Xchanging Ins-sure Services, Harman Wicks & Swayne and R J Kiln.