Sprint customers who buy the iPhone 4S will be able to roam internationally on GSM networks, but will not find themselves with unlocked microSIM slots, a Sprint representative tells Ars. While some initial reports suggested that the owners of the Sprint iPhone 4S might be able to pop a local GSM microSIM into their phones while abroad and avoid Sprint’s roaming charges, Sprint denies that that is the case.

On Tuesday, Macworld reported that the iPhone 4S would be sold with its microSIM slot unlocked. In theory, this means that the iPhone 4S would be able to use prepaid SIM cards on networks outside the US so customers wouldn’t have to pay for international roaming. Macworld said this would be the case for the Verizon iPhone 4S as well, after customers had had the phone and been in good standing after 60 days.

However, while Sprint will now support international roaming on GSM networks with the appropriate monthly plan, the company will not be selling the phone unlocked for use with international microSIMs. Ars asked Michelle Mermelstein, a Sprint wireless device public relations representative, to confirm that the Sprint iPhone 4S would not work with international microSIMs. “That is correct,” Mermelstein said. “I believe Verizon’s device works the same way.”

This corroborates some forum comments from Sprint customers, who state customer service representatives have told them the iPhone 4S can roam internationally on GSM with the appropriate plan, but can’t use SIM cards other than the one it comes with. If customers could get an unlocked phone from Sprint starting at $199, it would make the $549 unlocked version of the iPhone 4S somewhat redundant—according to Apple’s product page, the unlocked one “can also use a micro-SIM card from a local GSM carrier,” and only GSM networks in the US.

Update: Sprint has clarified for us one more time regarding the locked state of their iPhone 4S's: it will be sold unlocked, but will soon be locked, but can be unlocked again, if you ask nicely. The company's statement: