Scroll to the bottom of the pane that appears and click Legacy Google Voice.
Click the gear icon in the top-right corner of the page, and then click Settings.
Click the Phones tab, and then click Activate Voicemail below the phone that you want your voicemails transferred to Google Voice for.
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A box will pop up with instructions on how to complete the transfer of your voicemail function from your phone’s default system to Google Voice.
(Image source: ZTE USA Z-Community)
First, make sure that the telecom company listed beside “Your Carrier” is the one that provides your mobile phone service. If it isn’t, click Change Carrier and select the correct service provider.
Next, turn on your phone and dial the number that appears in the blue box, exactly as it’s shown. Place a call through to this number, and you should be all set! Click Done when you’re finished.
If you want to switch the voicemail system for your device back from Google Voice to your carrier’s default one, start by repeating steps 1 through 4. Then, when you get to step 5, after clicking the Phones tab, click Deactivate Voicemail below the phone that you want to disconnect from Google Voice’s voicemail system. Just like in step 6, a box will appear asking you to select your telecom provider and call a special number. Just change the carrier indicated if yours is different, and then place a call to the number that appears. Voila! You’re done!
Alright! Now you know how to enable or disable the auto-forwarding of missed calls on your mobile device to your Google Voice voicemail system. If you were instead looking for a way to permanently disable Google Voice by erasing your number or cancelling your account, see our guide here.