Siri is definitely one of the most popular applications for the iPhone 4S and iOS 5, but it’s becoming apparent that there are still some kinks for Apple to iron out when it comes to the artificial intelligence feature, which lets users make calls, set reminders and much more via state-of-the-art voice-recognition technology. A recently-discovered glitch allows access to Siri even when the 4S is locked.

“A default setting lets anyone who picks up the iPhone 4S to send emails and texts or access a user’s address book, calendar and personal information simply by speaking into it and activating Siri without a passcode, even when the phone itself is password-protected,” reads a Forbes article posted Monday. “Apple likely made Siri available when the screen is locked to facilitate easy, eyes-off, hands-free activation of the voice-recognition software.”

The personal assistant app is one of the major selling points for the 4S, which isn’t much of an upgrade over the iPhone 4 in the looks department but includes several interesting under-the-hood updates.

“No device debut is without its glitches, but a growing list of iPhone 4S concerns, coupled with last week’s reported problems with the iOS 5 and iCloud download and upgrade, may chip away at Apple’s reputation,” the article continues.