Call attendant on google voice

Change voicemail greeting based on who's calling
You can have one greeting for everyone who calls, or you can have different greetings based on who's calling.

Use different greetings for different people
Create a custom greeting for a group

Create a custom greeting for an individual

Record a standard greeting for everyone who calls
Create a greeting
Using a phone
On a phone, call your Google Voice number.
During the greeting, tap Star (*).
Enter your PIN, and tap Pound (#).
Open the settings by tapping 4.
Follow the instructions to record a new greeting.
Using a computer
Step 1: Find your voicemail settings

On your computer, open Google Voice.
At the top left, click Menu Menu and then Legacy Google Voice. Google Voice will look different, but you're in the right place.
At the top right, click Settings Settings and then Settings.
Click the "Voicemail & Text" tab.
Step 2: Create a greeting

In the "Voicemail Greeting" section, click Record New Greeting.
To use the greeting as your new default, check the box next to "Make this my default greeting for callers."
Enter a name for the new greeting, and click Continue.
Under "Phone to ring," select one of your forwarding phones.
Click Connect.
If you want to pick a greeting you already recorded, select it in the "Voicemail Greeting" section. At the bottom of the page, click Save.

Step 3: Record the greeting

Google Voice will call you on the forwarding phone you selected. Answer the call and record your new greeting when prompted.
If you selected your greeting to become your new default, after recording, the new greeting will become your default and the change will be automatically saved.

Source: https://support.google.com/voice/answer/115069?hl=en&ref_topic=1708439

In short, you need to record the greeting via Google Voice UI and not upload it.

If you have no further question, please do a favor to close this question.

Thanks!

Other responses are irreverent , I wasn't looking for a guide hot to set up a voice mail.