A redirect server is really a user agent server that generates 3xx (redirection) responses to requests it receives, directing the client to contact an alternate list of URIs. A redirect server will allow proxy servers to immediate SIP session Invites to exterior domains. Registrar[edit] A VoIP cell phone services company http://buzzgram.de/die-evolution-der-kommunikation-eine-einfuhrung-in-sip-trunking-voip-handys-softphones-und-voip-telefonanlagen/