How to turn off threaded sms on iPhone 4?

Hi all

I get lost in the way iPhone stores the sms messages. I cannot find back to both incoming and outgoing messages since they are not stored in one linear time sequence. The same functionality was also (by default)?) on the e-mails but happily that could be disabled. If it is impossible to turn off threaded sms I quite frankly must buy another phone.

Hope someone out there has discovered how to disable the threaded sms functionality.

Cheers

FR