Desktop Call Management

SIP enables a convergence at the desktop. Voice services can be assimilated into other applications to change the way we use our computers. The information management capabilities of the Internet can be used to transform communications systems and improve productivity.
Using SIP features such as user profiling, presence management and instant messaging, third party call control and integration with media, many great new services can be created by service providers or enterprise IT departments.
Here are some ideas:
Telephony-enable desktop applications such as your address book and diary - click-to-dial can be included in for fast look-up of contacts and to eliminate the need to continually dial the same old numbers. A central database can be used so that only a single instance of a contact needs to be managed and can be accessed from any SIP phone, PDA, mobile or desktop.
A presence management facility can be implemented on an enterprise's desktops. Upon registration SIP is aware of the location and call status of a user. This information can be presented in the form of "buddy lists" that display the status of users within a particular group. Within an organisation, therefore, it is possible to ascertain whether somebody is busy, available to take a call etc. This means that the engaged tone could become a thing of the past! Using the presence information a session could be established using any media, including instant messaging. At the click of a button, a message session can escalate to a telephone conversation or videoconference.
Combine this with user profiling based on a set of criteria such as presence, time of day, caller identity, call urgency or the content of databases and a very powerful tool can be created. Calls can be automatically directed to PC, mobile or voicemail depending upon the criteria used (e.g. identity, time). Together with information from your diary software this could even happen automatically around your schedule.
All the advanced telephony services inherited from the Intelligent Network are supported by SIP. This includes services such as, call hold, call waiting etc.