Dave Grohl has launched an interesting phone campaign for his upcoming ‘Sound City’ documentary, which collaborator Butch Vig says they hope will be ready to go this fall.

Dave Grohl has been working on a documentary about Sound City Studios, the now closed facility hosted the sessions that spawned classic albums like Nirvana‘s ‘Nevermind,’ Fleetwood Mac’s ‘Rumors,’ and Rage Against the Machine‘s self-titled debut.

It was revealed on Facebook that an easter egg had been added to the official website for the upcoming film, that being a phone icon that appears in the page’s upper right corner. When clicked, it displays an error-type message with the phone number 1-855-SND-CITY (763-2489). Fans can call the number and hear a few different recorded messages from Grohl, including a story about his first visit to the studio and audio of a possible jam session from the soundtrack.

Grohl has enlisted an all-star cast for the project’s soundtrack, which includes a ‘Nevermind’ reunion of himself,  Nirvana bassist Krist Novoselic and producer Butch Vig. “It’s a work in progress,” Vig tells NME of the project. “We’re not really sure how it’s all gonna end up at this point but its been fun. There’s still quite a bit more work to do and we hope to finish up in the next three or four months, and try get it all mixed and completed some time in the fall.”

Watch the Preview for ‘Sound City’

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