Passing Unsupported SIP Headers (SIP to SIP)
- Kelli Higdon
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In the SIP Protocol, converting header information is not performed for all headers. Some SIP Headers are either not supported on the IMG 2020 or don't have their equivalent in the other protocols so they are not translated or transferred. These headers, which are not supported on the IMG 2020 would normally be dropped. F-6295 Passing Unsupported Headers changes that behavior by giving the user a choice of whether a header, not supported on the IMG 2020, can be passed to the outgoing leg or dropped. The functionality is configurable through the SIP Headers object and by default is set to Disabled. Refer to the information below.
Call Flow Diagram
In the Call Flow diagram, the unsupported headers are relayed from the incoming requests to their outgoing requests when the feature is Enabled in the SIP Headers object that is configured on the outgoingSIP channel group.
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Table Of Supported Headers
Supported SIP Headers | |||
Call-ID | Content-Length | Timestamp | CC-Diversion |
Seq | Content-Type | Path | History-Info |
Via | Content-Encoding | Min-Expires | Anonymity |
Max-Forwards | Content-Disposition | User-Agent | Signal |
To | Session-Expires | Retry-After | Duration |
From | Min-SE | Subject | Reason |
Record-Route | Refer-To | Organization | RAck |
Route | Referred-By | Proxy-Authenticate | RSeq |
Contact | Event | Proxy-Require | User-to-User |
Require | Subscription-State | Unsupported | Replaces |
Supported | Allow | P-Asserted-Identity | Target-Dialog |
Expires | Server | P-Preferred-Identity | Priority |
WWW-Authenticate | Date | Privacy | Resource-Priority |
Authorization | Accept | Remote-Party-ID | P-Charge-Info |
Proxy-Authorization | Accept-Encoding | RPID-Privacy | Generic-Notification |
Content-Language | Accept-Language | Diversion | Â |
Standard Headers that will continue to be dropped
The table below displays a list of standard SIP Headers that are currently dropped and will continue to be dropped even when the feature is enabled.
Unsupported SIP Headers |
Content-Language |
Content-Disposition |
Server |
AcceptAccept-EncodingAccept-Language |
User-Agent |
Subject |
Organization |
Configuration
Initial Configuration
The procedure below explains how to configure the IMG 2020 to pass any unsupported SIP Headers from the incoming SIP protocol to the outgoing SIP protocol (SIP to SIP). Before configuring, the IMG 2020 must have an initial configuration created on it. Follow the Basic Configurations procedure before proceeding.
Create a SIP Profile (SGP) and then SIP Headers page
Right click on the Profiles object and select New SIP Profiles. The SIP Profiles object is a parent or container object. No configuration is needed here. Refer to the SIP Profiles topic for more information on this object.
Right click on the SIP Profiles object and select New SIP Profile. The first profile that gets created is a Default SIP Profile and cannot be modified. Disregard this profile.
Right click on the SIP Profiles object and select New SIP Profile again. In the SIP Profile object that appears, either enter a name that identifies this SIP Profile or accept the default name already entered. In this example the SIP Profile was labeled SIP_UnsupportedHeaders_En. Refer to the SIP Profile - SGP topic for more information on configuring the remaining fields in this object.
Right click on the SIP Profile object just created and select New SIP Headers. The Unsupported Headers Relaying field is by default, set to Disabled. Select Enabled from the drop down menu of this field to enable passing unsupported headers. Refer to screen capture below. Refer to SIP Profile - Headers topic for more information on configuring the remaining fields in this object.
Create a Remote Gateway
Create an external network element and link the SIP profile created with the remote SIP gateway. Follow procedure below to communicate with a remote gateway.
Right click on the Dialogic object and select New External Network Elements. The External Network Elements object is a parent or container object and no configuration is needed here. Refer to External Network Elements topic for more information.
Right click on External Network Elements and select New External Gateways. The External Gateways object is a parent or container object also and no configuration is needed here. Refer to External Gateways for more information.
Right click on External Gateways and select New External Gateway. Enter a name that identifies the gateway being configured. In this example the gateway was labeled UnsupportedHead_GW. Refer to screen capture below.
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Configure SIP Signaling
The configuration above displays how to configure the SIP Profile and External SIP Gateway so that the Unsupported SIP Headers will be passed. The next step is to configure the SIP signaling stack and SIP Channel Groups. For the functionality of this feature to work, the SIP Profile must be associated with an External Gateway linked to an outgoing channel group. Refer to the either the Configure SIP (Single SIP IP) or Configure SIP (Multiple SIP IP) topic for a procedure on how to configure the SIP stack functionality along with associated channels group and IP Network Elements.
Additional Information
The size of any single Unsupported SIP Header is unrestricted unless feature SIP Message and Header Restrictions has been enabled.
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There will be no restriction on the number of unsupported headers. The restriction will reside on the total msg length which is:
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The total size of any single Unsupported SIP Header that can be transferred is limited to approximately 2000 bytes
When unsupported headers are interleaved within standards headers, they will all be gathered in a list and grouped together in the outgoing SIP message. The unsupported headers are outputted in the same order as they were received.
Repeated unsupported headers are allowed.