Sure, I did that when I was having some trees installed. They still hit a line. I called back and they said "Oh, that's your domestic line. We don't care about that. We're only concerned from the main to the meter and you were clear of those, for the rest you're on your own."

Some lines also have a tracer wire that you hook a box up to, then a metal-detector like thing to detect the signal from the box. It's a bit more precise.