On call for jury duty?

I know this is a stupid question but..what does it mean "to call" 123-4567(press2) at 12:34 pm for a possible appearance at 5:43? Btw these are just examples. Do I actually go to the court and wait there? or do I just call and talk to some machine or person perhaps and wait for further instructions? I have to go on a monday..i dont want to make any mistakes and end up in jail LOL