How to Record a Google Voice Greeting From My Computer? [Solved]
If you have an audio file on your computer that you want to upload and use as your Google Voice greeting, see Stewart Nelson's answer to Can you import a sound file for your Google Voice greeting that plays when a call is sent to voicemail? If not, what is the best/easiest workaround it? .
If you want to use the mic on your computer to update your GV greeting, call your GV number from another service such as Free calling from your desktop , press * during the greeting, follow instructions to record your new greeting.
Use Google Hangouts, which is Google's VoIP and chat system, similar to iMessage/FaceTime or Skype. Hangouts should be available in the list as a "forwarding phone" in Google Voice, and you can have it call you on Hangouts in order to record a greeting that way.
You can also sign up for FireRTC, request a free incoming phone number, and then use that as your "phone" for recording your Google Voice voicemail greeting.
Note that you can never record a greeting at better than landline telephone quality, although landline quality is still better than cell phone quality.