Digital Barriers, a company which develops security and defence technology, has signed a contract with BT's monitored communications services business.Under the deal, BT Redcare, which is the UK's largest CCTV surveillance infrastructure and alarm signalling provider, will offer Digital Barriers' TVI wireless video surveillance products and services to its customers. As well as hardware and software sales, Digital Barriers will receive an annuity licence payment for each individual TVI connection.Group Development Director of Digital Barriers, Zak Doffman, said: "The public surveillance market represents a significant opportunity for Digital Barriers, and we believe this contract with BT will offer a best in class surveillance service to UK public and private organisations. "TVI has now proven itself around the world as a unique and disruptive capability, delivering usable surveillance video across restricted or narrow bandwidths, and providing network partners with unique control over bandwidth usage."Shares in Digital Barriers were up 3.9% at 168.5p at 08:30 on Tuesday.OH