The iPhone 4S officially went on sale in the US yesterday, and unsurprisingly, it has provided record-setting sales for at least two of the three major U.S carriers that offer the device.

AT&T on Friday confirmed to BGR in an email that it has activated a record number of iPhones and is on track to double its previous record of activations in a single day.

Sprint, which didn’t start carrying the iPhone until this month, reported its best ever day of sales in retail, web, and telesales for a device family in Sprint history, thanks to the launch of the new iPhone 4S and iPhone 4…

Sprint Product Chief, Fared Adib:

“Sprint today reported its best ever day of sales in retail, web and telesales for a device family in Sprint history with the launch of iPhone 4S and iPhone 4. We reached this milestone at approximately noon CT/1pm ET. The response to this device by current and new customers has surpassed our expectations and validates our customers’ desire for a truly unlimited data pricing plan.”

Sprint is the only U.S. iPhone carrier that currently offers an unlimited data plan to its customers.

These numbers probably explain the activation issues new iPhone owners were facing yesterday.

[The Loop]