The CM/GV integration is most likely going away. There was a recent post on G+[1] that called out May 15th as the end of unauthorized use of Google Voice > - F

The CM/GV integration is most likely going away. There was a recent post on G+[1] that called out May 15th as the end of unauthorized use of Google Voice > - Finally, we want to make Google Voice as secure as possible. There are a few third-party applications that provide calling and SMS services by making unauthorized use of Google Voice. These apps violate our Terms of Service and pose a threat to your security, so we’re notifying these app developers that they must stop making unauthorized use of Google Voice to run their services and transition users by May 15, 2014. [1]:https://plus.google.com/u/0/+NikhylSinghal/posts/MjyncJEbzxK https://plus.google.com/u/0/+NikhylSinghal/posts/MjyncJEbzxK