Two years after the birth of the manga a pilot film was released. It was a brief film of only 13 minutes that had the purpose of assay the response to a possible future anime realization of Lupin III. The pilot opens with a challenge call from Lupin to Zenigata from a public phone.

Previously unreleased remastered TV version of this pilot from a year 1971 was released in 1989. It was included on the Lupin III - Secret File OVA.

[Source: AniDB]