MY SAMSUNG CELL PHONE GT B5722 HAS A PROBLEM READI NG BOTH SIM CARDS WHEN YOU PUT ONE SIM CARD AT A TIME IN ANY SIM SLOT ITS WORKS FIND AND YOU GET SIGNAL BUT WHEN YOU PUT BOTH SIM CARDS IN IT ONLY READS ONE WITH SIGNAL AND OTHER SIM CARD WITH NO SIGNAL 1. I CAN CHANGE SIM CARD ON PHONE SETTING BUT IT REBOOT PHONE AND USE LOOSE THE FIRST SIM CARD SIGNAL

SOURCE: samsung sgh-e590 limited service

HI i have same problem with my samsung.

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follow this link and info

• http://forum.xda-developers.com/archive/index.php/t-274193.html

SOURCE: how do you remove sim card from a samsung knack?

Hi,
This phone is CDMA, so it does not have any sim card slot as it has inbuilt system which is directly operated by the service provider.
No other service provider is compatible with this phone.
Good luck

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i just bought a rugby that it frozen to ATT and am trying to unfreeze it also. I think you mean you have cellular one, not cingular??

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The sim card is inserted above the battery which is located on the back of the phone. The attached photo shows what you will see under the battery cover. First, turn the phone off. To remove the battery, start by removing the battery cover which is the back cover of the phone. Press on the back cover in the center next to the camera and pull the cover down towards the bottom of the phone. The cover should slide off. Slide the sim card, face down with the "notch" on the top right side of the sim up underneath the small metal receptacle designed for the sim card. If you do not see the receptacle, look for an etching of the sim card on the phone that is above and to the right of the sim card receptacle.