the modern equivalent is the ten codes, (as in "ten four" for "received") because the reason you say "ten" before the actual message code is to make sure you're transmitting and your pals are listening
I served as an Election Judge last week. Part of my duty--by law--was to walk outside the precinct doors at 6 AM and 7PM and shout "Hear ye, hear ye, hear ye! The polls are now open/closed!"
You'd best believe I put my back into it. I made sure I could be heard for a VERY long way.