SIP User's Manual 390 Document #: LTRT-65415
MediaPack Series
Parameter Description
[1] Enable
A GRUU is a SIP URI that routes to an instance-specific UA and can be
reachable from anywhere. There are a number of contexts in which it is
desirable to have an identifier that addresses a single UA (using GRUU)
rather than the group of UA’s indicated by an Address of Record (AOR).
For example, in call transfer where user A is talking to user B, and user
A wants to transfer the call to user C. User A sends a REFER to user C:
REFER sip:C@domain.com SIP/2.0
From: sip:A@domain.com;tag=99asd
To: sip:C@domain.com
Refer-To: (URI that identifies B's UA)
The Refer-To header needs to contain a URI that user C can use to
place a call to user B. This call needs to route to the specific UA
instance that user B is using to talk to user A. User B should provide
user A with a URI that has to be usable by anyone. It needs to be a
GRUU.
Obtaining a GRUU: The mechanism for obtaining a GRUU is through
registrations. A UA can obtain a GRUU by generating a REGISTER
request containing a Supported header field with the value “gruu”.
The UA includes a “+sip.instance” Contact header parameter of each
contact for which the GRUU is desired. This Contact parameter
contains a globally unique ID that identifies the UA instance. The
global unique ID is created from one of the following:
9 If the REGISTER is per the device’s client (endpoint), it is the
MAC address concatenated with the phone number of the client.
9 If the REGISTER is per device, it is the MAC address only.
9 When using TP, “User Info” can be used for registering per
endpoint. Thus, each endpoint can get a unique id – its phone
number. The globally unique ID in TP is the MAC address
concatenated with the phone number of the endpoint.
If the remote server doesn’t support GRUU, it ignores the parameters of
the GRUU. Otherwise, if the remote side also supports GRUU, the
REGISTER responses contain the “gruu” parameter in each Contact
header. This parameter contains a SIP or SIPS URI that represents a
GRUU corresponding to the UA instance that registered the contact.
The server provides the same GRUU for the same AOR and instance-id
when sending REGISTER again after registration expiration. RFC 5627
specifies that the remote target is a GRUU target if its’ Contact URL has
the "gr" parameter with or without a value.
Using GRUU: The UA can place the GRUU in any header field that
can contain a URI. It must use the GRUU in the following messages:
INVITE request, its 2xx response, SUBSCRIBE request, its 2xx
response, NOTIFY request, REFER request and its 2xx response.
EMS: Is CISCO Sce Mode
[IsCiscoSCEMode]
Determines whether a Cisco gateway exists at the remote side.
[0] = No Cisco gateway exists at the remote side (default).
[1] = A Cisco gateway exists at the remote side.
When a Cisco gateway exists at the remote side, the device must set
the value of the 'annexb' parameter of the fmtp attribute in the SDP to
'no'. This logic is used if the parameter EnableSilenceCompression is
set to 2 (enable without adaptation). In this case, Silence Suppression is
used on the channel but not declared in the SDP.
Note: The IsCiscoSCEMode parameter is applicable only when the
selected coder is G.729.
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