Turn off Iphone 4 text message swoosh sound

Does anyone here know how to turn off the swoosh sound when you send text message on Iphone 4? I tried everything to turn the sound off but I can't, unless I put my phone on silent by switch the button on the side of the phone to orange then it's off, but then again the ringtone also off too... I only want the swoosh sound to go off . Please help me! I have the updated version iOS5.1

I believe the sound has always been there(1st gen), don't know how to stop it.

You probably won't be able to get rid of the sound unless you jailbreak your phone and replace the sound file.

I had the same problem with my iPhone 4. There's not a simple way to do this, but I found a hack for it. You replace this file: (System/Library/Audio/UISounds/SendMessage.caf) with a blank file with the same name. You rename the file using iPhoneBrowser and then reboot. I found the step-by-step instructions here: http://forums.whirlpool.net.au/archive/1071157. Good luck!