The health advice service, which receives 6,000,000 calls a year, completed the two-year IT project to support the centralisation of its call centres last month.
Murray Bain, IT director at NHS Direct, said that previously the organisation had difficulty dealing with the volume of calls from patients, as calls were serviced from 22 different sites.
The centralised approach has allowed NHS Direct to balance call volume across the sites more efficiently, leading to an improvement in the quality of the service.
The project required the installation of 2,000 VoIP handsets and virtual call centre technology, as well as the implementation of the NHS's N3 network across 22 sites.
Based on network switches from Nortel and Nortel's Automated Call Distribution technology, the VoIP implementation uses business rules to route patient calls to the next available call centre agent.
Five technical hubs in Newcastle, Nottingham, Beckenham, Milton Keynes and Dudley have been equipped with Nortel Communication Servers and the Nortel Contact Center platform. Fifteen smaller sites run from these hubs.
Over the next six months, Bain plans to enhance the service by using computer/telephony integration to link caller ID information to NHS Direct's database of patients. This would enable agents to see a pop-up screen of patient details whenever they take a call.
NHS Direct is also working on closer links between its website and its call centre, which would allow patients using the website to speak to call centre agents.