A method and apparatus allows owners of electronic signs, such as retailers, real estate owners, other space owners, and content providers, such as advertisers, entertainment producers, event promoters, visual artists, and the general community to participate in an open content network, in which electronic signs are universally uniquely identified and then added to a network in a distributed fashion, after which content is selectively downloaded to the electronic signs. The times at which the content is presented are determined collaboratively by the owners of the electronic signs and the content providers. A mechanism that verifies whether the content is actually presented on the electronic signs is also disclosed.