Security: type=friend allows extensions to be enumerated

As reported in this thread http://www.freepbx.org/forum/freepbx/general-help/security-enumerating-extensions using type=friend for extensions results in extension enumeration vulnerability. There is really no point in using type=friend for extensions. Extensions should use type=peer by default. The circumstances where type=friend would be needed are unclear, given the fact the extensions are supposed to register. More info in this post from 2005: http://www.voip-info.org/wiki/view/Asterisk+SIP+user+vs+peer