U2 - Unknown Caller (Snow Patrol Remix) by U2collectibles published on 2012-10-23T04:29:13Z Artificial Horizon is a compilation album of remixed tracks. The triple-vinyl edition was released on May 14, 2010; this version included an MP3 for the Snow Patrol remix of the song "Unknown Caller" a Digital Download only available with this Triple Vinyl version. Vinyl color is purple when hold to the light A.K.A "purple vinyl" Genre Rock