Explanation/Reference:
Explanation:
Triggers are incoming events that invoke application which in turn starts executing the script associated with that application. For example, the incoming event can be an incoming call or an incoming HTTP request.
After you have created and configured your application, you need to create a trigger on the Cisco Unity Express module to point to that application.
Cisco Unity Express supports three types of triggers:

SIP triggers -- Use this type of trigger to invoke applications in Cisco Unified CME and Cisco SRST mode.
This type of trigger is identified by the phonenumber which is dialed to invoke the

desired application.
JTAPI triggers -- Use this type of trigger to invoke applications in Cisco Unified Communications

desired application.
HTTP triggers -- Use this type of trigger to invoke applications using an incoming HTTP request. Such a trigger is identified by the URL suffix of the incoming HTTP request. This type of trigger can only be used if an IVR license has been purchased and installed on the system.
Reference:
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/unity_exp/administrator/AA_and_VM/guide/ vmadmin_book/syscmp.html#wp1126512