The Federation was successful in secretly developing the technology in 2358, however the test ship for the device, the USS Pegasus, was lost. The Pegasus was rediscovered in an asteroid field in 2370 where the USS Enterprise-D recovered and used the interphase cloak before making its existence known to a Romulan Warbird in the vicinity. This event was quite illegal under the Treaty of Algeron and further use and development was prohibited. (TNG episode: "The Pegasus")