Bt has won a £75m seven-year outsourcing contract to provide and service Royal & SunAlliance's UK voice and data networks.
The deal gives RSA access to BT's network management resources, improving the composite insurer's flexibility.
Under the deal, 22 RSA staff will join BT Syncordia Solutions – a BT outsourcing and IT provider – in operational and project management disciplines.
RSA's manager of UK IT service, Viv Oldham, said: "Our new relationship with BT will allow us to exploit new technology rapidly, helping us to continue to meet our customers' changing service requirements."
BT general manager, Kim Pringle, said: "Outsourcing partnerships of this type are recognised as being increasingly important, given the changes in the insurance industry and the development of new technology-focused business models."