I think I misunderstood what you are trying to do. You want voicemails on the GV app, texts on the default messaging app. It's doable, but a bit flaky because when you integrate Google Voice, the idea is that it's a replacement for the default messaging app and sprint's voicemail. There are also caveats to doing this. It is a bit convoluted, so I'll give you the steps:
Originally Posted by PhishShticks
-Go into the google voice app on the phone. On the main Google Voice screen click your Menu button, then the *** More icon and choose Settings.
-Click the "Sync and Notifications" option.
-Leave the Text messages notification on. If you uncheck this, you will no longer get texts on your phone in the default app, and will only get them in the GV app.
-Now you have to decide what you want to do next:
*Option 1 is to uncheck the inbox notifications, which will keep you from getting the duplicate notifications when texts are received. The app may even complain to you about getting duplicates. Ignore it and click OK. The caveat to this is that you won't receive any notification of a voicemail from the GV app or the phone voicemail app, when you get one. The only thing you can do is make sure that GV sends you a text notifying you of a new text message. Make sure you check out your settings on the GV website under Voicemail & Text, and have it set to send you a text (SMS) when a voicemail is received. Also hit the last option to transcribe the voicemail so you still have the visual voicemail capability. Basically, you'll have to manually click into the GV app to listen to the message if choose to do so, because your only voicemail notification will be a text message that will take you to the default messaging app when you click on it.
*Option 2 is to leave the inbox notifications on, which will give you a notification of both new text messages and voicemails when received. Then go into the default messaging app, click the menu button and choose settings, and then notifications. Uncheck the "received" notification. Again, this will keep you from getting duplicate notifications on your text messages, but the caveat to this option is that if you click on the notification, it will take you to the GV app to read your text message. You will still get the message in the default messaging app as well, but you will have to manually click that app to read or reply to it. I'm guessing since you want to avoid the GV app for texts, this option probably isn't as good for you.
As stated originally, the GV app is meant as a free replacement for your text and voicemail service provided by sprint. No matter what, there's going to be issues with what you are trying to do, because you are basically trying to use GV for voicemail, and Sprint for text, but the service is designed as a singular replacement for both. If you aren't receiving voice mails left and right all day long, I'd use option 1. The only real downside to option 1 is manually launching the GV app to retrieve your voicemail.
Hope this helps!