actually on some nokia phones... tat's the feature...
if u use the tones on the phone it'll respond in a way that its soft first then loudest at the end...
my old nokia 6280(stolen) when i use... normal sms tone its softer for the first beep then slowly becomes louder...
u can try using the accending tone...
i didnt know until my fren told me that:)
for sony and others im not sure