
SIP 649
that Unity does not have any knowledge of which CallManager cluster a Unity subscriber’s
phone resides on. When enabling/disabling MWI, Unity must go off-hook as the sub-
scriber’s IP phone, and it must do this on a Cisco Unity-CallManager TSP port that is in the
same cluster as the IP phone. In essence, Unity uses the shotgun approach and sends MWI
requests out to each Cisco Unity-CallManager TSP cluster object that contains an MWI-
enabled port.
SIP
Session Initiation Protocol (SIP) is an emerging standard currently used for telephony,
presence, and instant messaging, among other services. SIP makes use of an Internet-like
distributed architecture ...