I have a Nokia 6225. I have message overwriting selected to "Sent items & inbox". Can anyone tell me how the messages are replaced ie. in what order?

What appears to happen is that all the sent items are replaced first and then inbox items (for incoming texts). So what I tend to end up after a period of time is 0 or 1 messages in sent items and about 80 in the inbox.

Is that how all the Nokia phones work? What would have been nice was if the phone replaced the oldest text *regardless* of whether it was in Sent items or in the inbox.