My daughter lost her iPhone and I need to find a cheap replacement. I have already purchased five iPhones and I’m not buying another for a while. Looking on Craigslist I see some android phones for $50-$100. I use att and I asked them if any of these android phones would work if I put my daughters sim card in. She got a new some card to use in an old phone. The att lady said they would would work fine even if they were from another carrier. I talked to a guy about a phone he was selling from u.s. cellular and he called u.s. cellular and they said it wouldnt work. Anyone know if these phones will work on the att network? Seems like there are a lot of Samsung galaxy and HTC desire phones for sale on Craigslist.
If the phone takes a SIM card there is a chance it will work. It’s going to depend on what carrier the phone is from and if the phone is unlocked or not. Some phones do not use a SIM card at all which will be useless to you.
As I understand it it depends on the phone and whether or not it is unlocked. This is something you would have to ask the seller.
Don’t know about US but in the UK most phones can be unlocked for any network, I have heard of some iPhone’s using a micro sim which complicates things.
On a phone note, I’ve got a desire hd and I love it, its used a lot for work - take photos of “issues” then email them to the office, has been dropped off the top of trucks and just comes back for more, it is, gordsapproved. 
plus I don’t do apple, can’t see the point in getting something that is a downgrade from my old phone, that has been the case at every upgrade since iphones came out.
The newer HTC is the sensation the the x models over here at least, I can’t recommend HTC enough to be honest although everyone I know with galaxy’s likes them a hell of a lot. I think android phones are much like xxxxfire - all work pretty much the same with just a few case details to differentiate
Iphones can be unlocked if you jailbreak it.
Get a phone with quadband gsm network.
eg. http://www.ebay.com/itm/New-Unlocked-Samsung-Google-Nexus-S-GT-19020A-16GB-Android-Cell-Phone-/160809102639
I think us cellular use cdma network. Different tech.
As long as she has a regular (not Micro SIM) you can use any GSM unlocked phone. Just make sure the phone is unlocked.
Since you don’t want to by another I phone for a bit, get a regular sim card. Check locally for shops that sell unlocked phones, new is IMO better than used for GSM phones, unless you buy a high dollar phone. There are many places that sell good unlocked phones here in the city, so there might be one in your area too.
Here is a place I have walked into and bought a few phones. I think you can buy online from them.
http://www.mobilecityonline.com/wireless/store/gsm_unlocked_phones.asp
EDIT: also make sure the phone you buy works on the band that aT&T works on. If you get a quadband you are good , just watch for phones that are only dual band as it may not work if its the wrong bands.
Thanks for the help guys.
Also don’t forget that the GSM frequency to make phone calls is different from the UMTS (3G / 4G internet) frequency. I have an Android smartphone that works on the GSM phone networks in this country and it connects to 2G (Edge) internet, but not to the 3G network, because they use a different UMTS frequency here.