What is 811, and what happens when you call?
811 is the free national "call before you dig" service. You report where you plan to dig, member utilities send locators to mark their buried lines with paint and flags, and only then is it legal to dig.
Every state routes 811 to its own one-call center. You give the dig site, the type of work, and when you plan to start. The center notifies every member utility with lines in the area, and each one sends a locator or responds "clear."
The rules that matter
Wait times and ticket life vary by state, but the pattern is the same: a required waiting period before you can dig, a window in which you must start, a period the marks stay valid, and a tolerance zone around each mark (typically 18 to 24 inches on each side) where you must hand-dig or soft-dig.
New Jersey is a good example of why the numbers are worth getting right, because there are three of them and they are easy to confuse. Under N.J.A.C. 14:2-3.1 you give at least three full business days notice, you must begin work within 10 business days of the notice, and the markout then stays valid for 45 business days from notification, provided you maintain the marks. People routinely quote the 10 as though it were the expiry. It is not; it is the deadline to start.
What it doesn't cover
811 marks public utility lines. Private lines, like the gas run to a pool heater, an irrigation system, or a well feed, are not marked. If the property has private utilities, a private locate service is a separate call.
Digging without a valid ticket risks lives first and fines second, and a hit line without a ticket is on you. Track ticket numbers and expiration dates on the job, and re-call before marks lapse mid-project. That is what 811 ticket tracking is for: the number and the dates sit on the job rather than in a spreadsheet somebody has to remember to open.