Pre-paid phone cards

A dear friend who going into hospital soon to deliver her second child (and trying for a VBAC -- keep your fingers crossed for her!) was asking me about pre-paid phone cards:

I am thinking I need to get [a pre-paid phone card] for when I am in the hospital and need to call people to tell them I had the baby. I can make local calls from there but not long distance ones. (...) You are not allowed to use cell phones in the hospital.

(You aren't allowed to use cell phones in a hospital? Is this a revenue racket for the hospitals, or is there any kind of legitimate reason for it?)

At any rate, I don't use phone cards so I promised to ask around.

I've heard that ATT's prepaid cards are expensive. Can anyone recommend a better option?