Chapter 7 Firewall for FortiOS 5.0 : Firewall objects : Example Scenario: Using FortiGate services to support Audio/Visual Conferencing : Creating the IPS Security Profile
  
Creating the IPS Security Profile
This is by no means the only way to set up this IPS filter, but it is the way that the fictional System Administrator wants it set up. Yours may be different.
Go to Security Profiles -> Intrusion Protection -> IPS Sensors.
Create a new sensor
Name
A-V_Conference-incoming
Select OK
In the newly created sensor, create a new IPS filter.
Sensor Type
Filter Based
Filter Options
Advanced
Severity
Critical
High
Medium
Low
Target
Server
OS
Windows
Application
IIS
other
Protocol
Use the [Show more...] option
HTTP
LDAP
SIP
SSL
H323
Packet logging
enabled
Based on these filters there should be somewhere in the neighborhood of 750 signatures that the FortiGate will run traffic against in the IPS engine.