User ‘Pack’ on IRC (#iphone-uikit) has discovered an easy way to use your own prerecorded sound files as your voicemail greeting. This is great for if you want to use a prerecorded novelty greeting or if you just don’t want to record your greeting through the less-than-hifi iPhone microphone.

Here’s the process:

1. Take the sound clip you want to use and covert it to an .amr file and save it as “greeting.amr”
2. On your iPhone, go to voicemail and start recording a voicemail greeting as you normally would
3. Press “Stop” to end the recording. It doesn’t matter what you record at this point
4. Before clicking “Save”, use your favorite method to copy your “greeting.amr” over “/var/root/Library/Voicemail/greeting.amr” on the iPhone. You can use scp, sftp, iphonedisk, iPhoneInterface, etc to copy the file
5. Click “Save” on the iPhone. It will now upload your prerecorded greeting to AT&T.
6. Call yourself to test it out!