Recently I have been having issues logging in to the iPhone Google Voice application called GV Mobile Free. It appears some of those issues may be resolved by upgrading to the latest version of GV Mobile Free which is 1.22.1. The only problem with that is the fact that I currently cannot find the newest version or any version for that matter in the iTunes store. Currently I have GV Mobile Free version 1.2 installed and the log in issues will pop up a credentials message shown below.
Recently Gizmo5 added the ability to configure your Google Voice account within the Gizmo5 interface which allows for you to configure any SIP device (soft or hardware) to have free voice. I happened to have a SPA-2000 around so the below describes how to configure a Sipura SPA-2000 using Gizmo5 and a Google Voice account for free voice. For this howto you will need a SPA-2000, a Gizmo5.com account, and a Google Voice account.