I am having difficulty configuring polycom phone to failover when one proxy server is not available.  I've configured the phone to use sip naptr records that  provides two proxy server names.  I've configured the "retry timeout" and "retry max count" however, when proxy1 is not available, polycom phone does not send requests to proxy2.    

  Is there any other option I need to configure?   I've tried this on polycom 430 and 601 models.