I'd like to know what's the best PRE-PAID mobile phone service to call mainly CA mobile phones and other nationwide land lines (mainly NON CA). It needs to be a GSM- Sim card based system. Especially, I am interested in costs, ways of recharging, and any other details. It would be great if it can also do international roaming.
I prefer services that charge you only for what you ACTUALLY use, without any daily fees or anything, no free calls, no special services. PURE calls and SMS is enough.

Thanks for any ideas!

I use T-mobile.

Can be charged via the Internet, top up card or on the phone itself.

Once you have topped up to a value in total of $100, minutes remain valid for 365 days. Before you reach the $100 validity depends on the amount you top up. No service charge just a charge for what you use.

I purchased just the sim card and put it into a GSM phone I already had.

Minutes can be used anywhere in USA not tried to call internationally on it as have no need.

Great! Exactly what I needed. Thank you!

I bought a GSM phone on eBay and purchased a SIM card for Cingular (now AT&T). Used this for over a year with no problems. Similar to T-mobile - I only get charged when I use it and I always buy in $100 increments so the minutes are good for a year. I like that it is free for me to call other AT&T subscribers...sometimes it takes forever to use my minutes.

Its free for you to call other AT&T subscibers (cell & landline?) even though you are on prepaid? My husband had t-mobile prepaid for a little while when he got here, and for sure they did not offer free calling to other T-mobile customers!

AT&T prepaid for sure lets you call other cell phone subscribers for free but I am not sure about land lines of theirs.

I don't think the free calls apply to AT&T landlines - only cell phones. My husband and I both have AT&T cell phones (he is on a plan, I am on the prepaid). He has a Nevada number & mine is from California so I thought we would at least get charged long-distance, but our calls are always totally free, no airtime charges or anything. I wish all my friends were with AT&T so we could talk for free! There is a charge for text messages though.

AT&T have two pay as you go plans. The free calls to mobile numbers only applies to the plan that charges $1 for any day you use the phone, in addition to the call charges. The plan that doesn't have the $1 charge but a higher charge per call does not include free mobile to mobile calls.

Also with AT&T you have to top up each time for $100 to keep the minutes alive for a full year, lesser amount last for up to 90 days. With T-Mobile once you have topped up to a total of $100 all further minutes last a year. Last time I had quite a few unused minutes left so I just topped up for $10 and that set the expiration for another 365 days.

I bought a prepaid sim off of ebay and sent it to my wife overseas before she got here. I activated it shortly before she arrived so she could just put it into her phone. This let her have an instant phone number as soon as she arrived in the US.

We prefer Tmobile. We are actually on a plan, but I've checked into Cingular(ATT&T or whatever they are calling it now) and compared them. The only difference is that ATT has better phones, but Tmobile offers ---international text messaging--- Cingular does NOT. (At least at the time I compared them late last year.) International Texts are 15cents each. Cheaper than calling overseas for a short conversation or to alert to get online. Both offer international roaming, but I would personally get an unlocked phone (I have!) and just use a prepaid sim in whichever country you are in. Much cheaper that way.

International roaming is great if you have a blackberry (i'm not sure about other smartphones). i have an unlocked phone, but i always take my tmobile blackberry too. i pay an extra fee for unlimited email, and then i pay a very small per MB surcharge for data. beats an internet cafe any day.