This is just a bit of info for those going budget:
Back in 2000 when I did my first cross country solo tour I used public phones to call relatives. That worked very well. Last summer (2012) I did another cross country tour and was not able to make any public phone calls any more, because:
1. Most public phones were removed
2. If a public phone was present, it did not work
I was only able to make phone calls because local people out of kindness let me use their phone.
Now, some people might ask why I did not carry a cell phone: I'm from Europe and I'm not interested in:
1. Buying a brand new US phone on arrival - and waist my time on that instead of cycling
2. Using my own European cell which becomes crazy expensive to use.
plus, you need tri-band.