Old Postpaid SIM to be used as Prepaid?

No - once you activated the new SIM with your Galaxy the old SIM associated with your phone number was deactivated by at&t.  Deactivated SIMs cannot be reactivated and used with a different phone number. 

If you want an additional prepaid account/phone number, you'll need to obtain a new SIM and set up a prepaid line of service.

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@UsedSIM wrote:

Thanks for the response hme.

 

Next question..

 

ATT prepaid plan (on website) appears to require a purchase of a GoPhone device.  There isn't an option to purchase just the SIM.  I know you can buy the unactivated prepaid SIM from Amazon and Ebay, so does that mean ATT store will sell just the SIM and plan without the device?

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You're welcome. 🙂

You shouldn't have any trouble obtaining a SIM at your local at&t corporate store, and AFAIK there won't be a charge for the SIM if you'll add airtime to the account while you are in the store.  Just let the store personnel know that you have an old Cingular/at&t phone that you intend to use for the prepaid account; and in fact I'd take the old Razr with you so that you can be certain the account is set up and working correctly before you leave the store.

Thanks for the response hme.

Next question..

ATT prepaid plan (on website) appears to require a purchase of a GoPhone device.  There isn't an option to purchase just the SIM.  I know you can buy the unactivated prepaid SIM from Amazon and Ebay, so does that mean ATT store will sell just the SIM and plan without the device?

I guess so.

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@UsedSIM wrote:

Thanks for the response hme.

 

Next question..

 

ATT prepaid plan (on website) appears to require a purchase of a GoPhone device.  There isn't an option to purchase just the SIM.  I know you can buy the unactivated prepaid SIM from Amazon and Ebay, so does that mean ATT store will sell just the SIM and plan without the device?

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It has been a while but I did buy just the SIM with some starup airtime right from a store.