It helps to backhand them after the stern,You can always tell which people have never had kids. Sometimes even when kids are "quiet", their not, especially when under the age of 5.
I don't have kids of my own, but have dealt with many, my niece helping my mom out in her daycare. You give then a stern, strong, "knock the crap off" they'll listen. You can't be passive-aggresive and wish washy and especialy the menqatlity of "Kids will be kids."
A stern, "Be quiet someone is on the phone." should suffice, not to mention raising them from the time they can walk to behave.
"Be quiet".
