You can use any media recording application to record a greeting. The audio (WAV) file must meet the following requirements:
- 8 or 16 khz
- 8 or 16 bit mono
- u-law, A-law, or PCM
- Maximum file size of 2MB (or approximately 4 minutes of playback).
Go here to learn how to upload your Auto Attendant greeting. Go here to learn how to upload your voicemail greeting.