I have an N2000 switch running code 6.6.0.13 with a some APs, VOIP Phones, and some other things supporting a small building. Whenever I update the code to 6.7.1.9 or 6.7.1.13. In each instance, the only service that doesn't return is VOIP. The phones are on, but they are not working. They display the no service warning. All other services on the switch appear to be working fine. 

Thankfully when I revert back to the old code, service returns to the VOIP phones. I've gone through the release notes a few time. What am I missing?