There is also a trick to calling home for FREE:
Find a DSN phone on base (Usually a few around. Some are set up for soldiers' use.)
Call a local base DSN number and tell them it's a "moral call from overseas, please connect me to a local number" and they will ask for a number to connect to (home, friends, etc).
Usually it's about 15 min and then it drops, but if the lines aren't busy they won't cut off the call.
Here are the local DSNs:
Natick Labs, MA: 312-256-4001
Hanscom, MA: 312-478-4441
Westover, MA: 312-589-1110
New Boston, NH: 312-489-2000
Portsmouth, NH: 312-684-1000
This is also a way to get full use out of a phone card: have them connect the call to the phone card number. then its US minutes being used not International.