»For king and country

I'm trying to figure out whether I have to show up at the Superior Court on Monday: I received a summons for Jury Duty in the City and County of San Francisco. The phone system tells me (after I key in 1,1,1,my juror badge #, and 1 to confirm) that "No-one is available to take your call. The next time Jury Clerks will be available is May 3rd at 8:00 AM".
And the web site doesn't offer an interface to this information.