am 718e0033: Merge "SIP: add SERVER_UNREACHABLE error code." into gingerbread

Merge commit '718e0033e69fa7d1db12242324ab9098ac430bf5' into gingerbread-plus-aosp

* commit '718e0033e69fa7d1db12242324ab9098ac430bf5':
  SIP: add SERVER_UNREACHABLE error code.