In another thread folks are referencing PO what is that acronym? Checked TER FAQ and google. No bueno.

Phone Operator or Booker.  Determines if pre-book is allowed or not.  Usually have to confirm appointment by 9 am or no soup for you.

So another term for booker/scheduler. I suppose in some context it might be police officer but hope that was not the case.

NorCal PO = SoCal booker.
What about other regions, are there other terms used?

PO is phone operator, yes.

then the term often becomes, "Shithead."

Booker, mama-san (which is really incorrect since they are all Korean owned).

Long long ago, in a country apparently far far away, the most common meaning was "Post Office".  Do you remember those?  
.
PS for the sarcasm impaired:  skip this post, or be PO'd.

Good point, lol. I forgot about that.

This has come up before:  
http://www.theeroticreview.com/discussion-boards/k-girl-113/po---4759
PO is used for too many other things, even as a common abbreviation for Parole Officer ... not that I would know anything about that.  
.
A "phone operator" is not a booker! A phone operator sits at a switchboard and, using wires, connects your call to the party to whom you are speaking. If the line is busy, she might take a message ... using a pencil and a pink message pad. Sheesh.
.
Just say booker. Just say phone girl or PG. And even when it's a guy who does the booking, it's still "the phone girl told me about someone new ..."  
.
PO is not clear even when you think the meaning should be obvious. JUST SAY BOOKER! (Do I need a hashtag for that?)

Imp, I will disagree here. Your version of phone operator was true maybe in POTS times.  

the FIRST thought that came to your mind was something other than Parole Officer?   LOL

The winds of change are upon us.  Bend like bamboo or break like the mighty Oak in the winds of change.

In the modern day of PC terms we should not even use booker.  

In the hobby I always interpreted it as Provider Office. Especially since they do so much more than answer the phone. A good PO can make or break your experience.

EC  =  Ejaculation Coordinator?   (Which would make the girl an ET  =  Ejaculation Technician)

Washington DC area Booker or old school is mama-san.

USC means Trojan. Which makes sense with "bookers" on many levels, if you think about it

I had notices the USC connection but not a huge sports fan so missed that link.

But let's not forget, Trojans always fail under pressure.  

I am of course talking about the 2006 Rose Bowl where Vince Young put the Longhorns squarely on his back and came back to win that game after being down early as underdogs winning me ten grand in the process. Even better I was on a ten day vacation in Costa Rica at the time where I set a personal record of doing 40 different chicas during that ten day period.  

I'm a big sports fan, so youll hear a lot of sports puns... mostly bad ones... from me, lol.

An epic Trojan fail!

I think the line was USC -7 1/2, I didn't take the points, I took the +260 and parlayed it with the over and at half time I doubled down and did it again for the second half. It was one of the most enjoyable games I have ever watched, not to mention the fact I watched it at the Blue Marlin Bar in San Jose Costa Rica surrounded with maybe a dozen or two other gringos along with maybe 200 hot Colombian, Nicaraguan and Tica putas. Ah, those were the days.

As they say, your username checks out

I do miss those "good old days" at the Hotel Del Rey in Costa Rica, back in '05-'06 even the hottest of the hot chicas down there only charged about $40 for an hour or so, and you could get TLN (Toda la Noche) for about $100, and the place was constantly PACKED with pussy, usually anywhere from 5-1 at worst up to more like 10-1 chicas to hombres, it was like living the life of a rock star and I was still young enough to fuck several girls a day, every day for a week or more at a time. My poor old body just can't do that anymore today, especially not doing it while drinking 20 hours a day on top of all the fucking. Ah to be young again, or even "middle aged" lol