1. A method for testing performance of a contact centre using virtual agents, the method comprising: defining at least one behaviour profile that specifies behavioural response of a virtual agent to a call to the contact centre; registering at least one virtual agent into a contact centre server to respond to calls to the contact centre; generating calls to the contact centre to simulate actual enquiries to the contact centre; assigning the at least one virtual agent to respond to the generated calls according to the at least one behaviour profile; and recording details of calls handled by the at least one virtual agent, wherein the at least one virtual agent simulates the behaviour of an actual agent and in concert with the generated calls simulates operation of the contact centre.