Added properties for handling the server advertised voicemail URI

Ignore-this: a5f8132cb378e289cf04eac099874a92

darcs-hash:20100916144311-b22ec-774db21c1f775418c103c175ed709ee223ae2c00
Removed some unnecessary NotificationCenter instantiations

Ignore-this: 1d918e194da7bcc824a61b4c262751d7

darcs-hash:20100916144859-b22ec-dc00c065919aa1cb2f483e195a02d6f73478a1e7