Federal jury service

I received a jury summons for the federal district court next month, and I'm curious exactly how it works. It sounds like you have to call every night to find out if you actually have to go in, even before the day you're supposed to report. Am I understanding that right? Sounds very inconvenient, especially if you work a public-facing job. And I've heard these trials can last weeks? I would hope they're at least interesting. I'd love to hear any firsthand experiences.