iotum offers a Voice 2.0 call management service, which intelligently filters, ranks, and prioritizes calls based on their relevance to you. Using your contextual information and preferences, iotum knows who's calling, whether you want to take the call, and which phone you want to use.

For gathering context, iotum currently provides a Microsoft Windows application and a Microsoft Outlook plugin, which gathers contextual information from the user's contacts, calenders, and MSN presence, and forwards that to the iotum server.

The iotum server offers an xml-rpc web service to make this information available to call routing applications such as pbxs or phone switches. The pbx or soft switch can integrate with the iotum service by making an xml-rpc call and rerouting the call based on the returned action information.

via Building the iotum Asterisk Module – O’Reilly Media.