Header manipulation is used when specific components within SIP messages need to be modified.
The reason for header manipulation are:
To resolve SIP protocol variances between different vendors
To hide SIP topology by removing VIA headers
Header Manipulation Actions
You can modify non-essential headers in SIP messages using header and parameter profiles. The
following information summarizes the supported actions:
Pass the header unchanged (whitelist functionality).
Conditionally pass the header unchanged.
Remove the header (blacklist functionality).
Conditionally remove the header.
Replace the name of the header. The replacement name cannot be that of a vital header.
Conditionally replace the header content (appearing after the “:”).
Add a new instance of a header to a message regardless of whether or not the header already exists.
Add the first instance of the header to the message, if a header with this name does not already exist.
*Header manipulation is generally performed prior to routing of calls, however, can be modified after routing as well.
Header Manipulation Operation
Ingress
When the SIP profile has header manipulation for ingress configured, SIP headers get modified, then the call is sent to the routing engine.
Egress
When the SIP profile has header manipulation for egress configured, SIP header get modified as the call leaves the SIP profile.
Header Manipulation Configuration Options
Similarly to call routing, there are two ways of configuring header manipulation rules:
WebGUI/Basic Header Manipulation
Advanced XML Header Manipulation