About the Presentation Indicator
When address information represents a telephone number, the relevant information can appear in the Calling Party Number information element (IE). This IE contains the caller’s number, information about the number, and presentation and screening indicators found in octet 3a. In order to prevent a calling party number to be passed through, the presentation indicator parameter (octet 3a) in the Calling Party IE must be set to a value other than 00.
In a H.323 to SIP IWF call, octet 3a in the Q.931 message indicates the caller’s preference for CPID restriction. If bits 7 and 6 are set to (0 1), the presentation is restricted and the outbound SIP INVITE from the IWF stack must be constructed as such.