can i use any cingular/AT&T sim card for any phone?

[SB]

i got a phone but its an older fone and there is no sim card and im not sure what the name of the fone is so i was wondering if i needed a certain sim card

[CC]

You should be able to use it, but some networks require you use their phones, because some other phones can not get a signal for internet etc. Check with your service provider to be sure. They should be able to tell you if you can or not.

[ClayW]

You need a certain sim card

[michelle]

You can use your sim card on any phone as long as it is a cingular/at&t phone & sim card.

[JonP]

unlock it to any carier

[JonP]

unlock it to any carier

[adeg_1992]

only on at&t phones

[noahsmommy]

only active on Cingular/AT&T network... Sprint and Verizon phones won't work

[geeth]

hi codes are the best method to unlock your phone .you can get the codes from unlocking4free here they ask the imei number of your mobile .finally they generate the codes to unlock your mobile at free of cost.