Sometimes in life, and I can't stress the word sometimes enough, having a 'wacky' SMS tone for your iPhone 4 can be worthwhile. But before we tell you how you can personalise your SMS tone, you have to promise not to set the following as your message tone; any song from the current top 40, the Angry Frog song, the ironic Nokia tune, the Dixie horn or (if you were born earlier than the 80s) the Dukes of Hazzard horn, any Little Britain catchphrase and certainly not any celebrity alerting you that you have a message.
Okay, now we've got the ground rules out of the way, we can get down to the business of changing your message tone on your iPhone 4.
The first thing you have to do, is Jailbreak your iPhone. If you don't do this, then you cannot change the message tone settings. Of course it is not advisable to change the settings of your iPhone unless you are a expert user. See How to Jailbreak an iPhone for a full guide of what to do and the risks involved.
Download and install the program iPhone Explorer. This will give you access to the hidden folders on your iPhone.
Connect your iPhone to your PC/Mac, open iPhone Explorer, select your iPhone 4 and open Root Directory > System > Audio > UISounds. This is the folder where your iPhone's SMS received tones are stored.
Next you need to copy the exact file name of one of the existing SMS tones in the folder. It will read something similar to 'sms-received1.caf'. After you have done this, you need to change the name of the file you want to use as your new message tone to the filename you have just copied. Once you have done this you simply put the new message file into the UISounds folder and replace the old one.
Now restart your iPhone and change the SMS tone on your iPhone. This can be found in Settings > Sounds > New Text Message
And that my friends is that!