ISDN Headers

What are ISDN Headers?

ISDN headers are used to set message information & send via ISDN protocol.
NVG maps ISDN information elements into ISDN/SIP messages in order to pass specific ISDN parameters to the end user.

NVG uses ISDN headers to pass ISDN variables from ISDN->ISDN & ISDN->SIP (i.e. CIC, NADI, RDNIS..etc)

Passing information from ISDN->ISDN/ISDN->SIP

By default if NVG receives ISDN message with any of the ISDN-Headers defined below and the ISDN-Headers feature is enabled, NVG will automatically populate the associated ISDN messages with the specified values.  ISDN-Header will only be considered if it is properly formed, and matches the string found in the "ISDN-Header" column below, and is case-insensitive.

FreeSWITCH - How to Use ISDN Headers

ISDN->ISDN (Receiving ISDN Header From NSG) 

Unlike SS7 headers ISDN header will be stored in variable "Z" with Z being the ISDN header.
The example below will print to the log/console the value of the ISDN header that contains the the sub address type of calling party

Example:  <action application="log" data="The CID Sub Address Type Is: [${isdn.calling_subaddr_type}]"/>

SIP->ISDN (Sending ISDN Header To NSG)

You can populate an ISDN header by using the "export" application in FreeSWITCH.
The example below shows how to set the Calling party screen indicator value to 4.

Example:    <action application="export" data="isdn.cg_pty2.screen_ind=2"/>
 

NOTE: 

1. ISDN-> ISDN means when parameters can be exported from ISDN to ISDN.

    ISDN->SIP means when parameters can be exported form ISDN to SIP .
    If "Y"  than that parameter can be set and exported/set. If "N" then it is not. 

Complete List of ISDN Headers
 

Calling/Connected Number Parameter

Calling/Connected Party Subaddress Parameters

Called Party Subaddress Parameters

User to User Parameter

Progress Indicator Parameter

Network Specific Facility Parameters