CUCM 9.1 gives us a little christmas present

Native paging is now included in CUCM 9.1 using informacast (which is a good product I have used it myself :)

Paging

Now included with Unified Communications Manager is the Singlewire InformaCast product that provides paging capabilities for users to make point-to-point, or group pages, to and from Cisco IP Phones. The software and documentation for the InformaCast product is on a separate DVD included with the purchase of Unified Communications Manager. It is also available online as a software download on cisco.com.
The InformaCast product is divided into two categories, basic and advanced functionality. The basic paging features allow paging between Cisco IP Phones to groups and zones that the administrator configures. An unlimited number of groups is possible but with a maximum of 50 users total in each group in basic paging. Basic paging is provided as a new Unified Communications Manager feature at no cost. If there is a requirement for more than 50 users in a single group or for higher level capabilities, the advanced features of InformaCast are required and are highly recommended.
The advanced features of InformaCast include:

• Paging and Emergency Notification to All Users
• Paging to Overhead Analog and IP Speakers
• Bell Scheduling
• Prioritizing Emergency Notifications with Call Barge Option
• Pre-Recorded and Text only pages
• Integration with Social Media Sites for Notification
• Email and SMS Mass Notification
• Call Number Monitoring - 911 Alerting
• Integration with Jabber clients

There are numerous additional features of Advanced Paging. To determine if Advanced Paging/Notification is appropriate for the end user's Unified Communications Manager deployment, there is a 60 day trial of the advanced functionality to evaluate the higher level features. After installation of the software, there is an option to begin the demonstration period for full access to all capabilities. To retain Advanced Functionality after trial or if this functionality is required at the time of the Unified Communications Manager purchase, the Advanced Paging/Notification functionality can be purchased as a perpetual license from SolutionsPlus or as a subscription directly from Singlewire. For more information on the product's capabilities or for sales questions, contact Singlewire or refer to the documentation and support information included with the product.