I’ve been spending three days of each week shooting my new TV series, “It’s All Geek to Me,” which will be airing on two of the farm-team Discovery channels starting in February. (It’s slated for Discovery HD and Discovery Times, which may have a new name by the time the show airs.)

One episode is all about cellphones, and how to fight back when you’re feeling overwhelmed and bilked by the carriers.

We dug up the following delicious money-saving keystrokes for each of the four big carriers.

First: the keystroke that interrupts a voicemail message. It doesn’t just cut short the “Hi, this is Casey, I’m not here right now” message–it also eliminates the TWELVE-SECOND digital lady who says, in an effort to run up your bill: “When you’re finished recording, you may hang up, or press 1 for more options” (and so on). Every time you use this keystroke, you’re saving yourself money.

Verizon or Cingular: press *

Sprint: press 1

T-Mobile: press #

(Of course, you have to know which carrier your friend uses, so you know which keystroke to use!)

Second: the keystroke that reveals how many of your allotted anytime minutes you’ve used up so far this month, so you won’t inadvertently go over the limit and rack up insane bills. Three of the carriers use variations of the dialed-out word MIN (short for minutes, get it?), but there are subtle variations in the preceding and following keystroke:

Verizon: dial #646

T-Mobile: dial #646#

Cingular: dial *646#

Sprint: *4

I swear–if I had a nickel for every penny I’ve saved my readers…