Interworking Sip Prack Messages; Interworking Sip Session Timer; Interworking Sip Early Media - AudioCodes Mediant 1000B User Manual

28.8.4 Interworking SIP PRACK Messages

The device supports interworking of SIP Provisional Response ACKnowledgement
(PRACK) messages (18x). While some UAs may not support PRACK (RFC 3262) others
may require it. The device can be configured to resolve this interoperable issue and enable
sessions between such endpoints. SIP PRACK handling is configured using the IP Profile
parameter, 'SBC Prack Mode':

Optional: PRACK is optional for these UAs. If required, the device performs the
PRACK process on behalf of the destination UA.

Mandatory: PRACK is required for these UAs. Calls from UAs that do not support
PRACK are rejected. Calls destined to these UAs are also required to support
PRACK.

Transparent (default): The device does not intervene with the PRACK process and
forwards the request as is.

28.8.5 Interworking SIP Session Timer

The device supports interworking of the SIP signaling keep-alive mechanism. The SIP
standard provides a signaling keep-alive mechanism using re-INVITE and UPDATE
messages. In certain setups, keep-alive may be required by some SIP UAs while for others
it may not be supported. The device can resolve this mismatch by performing the keep-
alive process on behalf of SIP UAs that do not support it.
For configuring the handling of session expires, use the IP Profile parameter, 'SBC Session
Expires Mode'.

28.8.6 Interworking SIP Early Media

The device supports various interworking modes for SIP early media between SIP UAs
(i.e., IP Groups):

Early Media Enabling: The device supports the interworking of early media between
SIP UAs that support early media and those that do not support receipt of early media.
Early media can arrive in provisional responses to an INVITE request. The device
forwards the request of early media for IP Groups that support this capability;
otherwise, the device terminates it. Provisional responses whose SDP are suppressed
are changed to a SIP 180 response. This feature is also supported for delayed offers.
This is configured using the IP Profile parameter, 'SBC Remote Early Media Support'.
The device refers to this parameter also for features that require early media such as
playing ringback tone.

Early Media Response Type: The device supports the interworking of different SIP
provisional response types between UAs for forwarding the early media to the caller.
This can support all early media response types (default), SIP 180 only, or SIP 183
only, and is configured by the IP Profile parameter, 'SBC Remote Early Media
Response Type'.

Multiple 18x: The device supports the interworking of different support for multiple
18x responses (including 180 Ringing, 181 Call is Being Forwarded, 182 Call Queued,
and 183 Session Progress) that are forwarded to the caller. The UA can be configured
as supporting only receipt of the first 18x response (i.e., the device forwards only this
response to the caller), or receipt of multiple 18x responses (default). This is
configured by the IP Profile parameter, 'SBC Remote Multiple 18x Support'.

Early Media RTP: The device supports the interworking with remote clients that send
18x responses with early media and whose subsequent RTP is delayed, and with
remote clients that do not support this and require RTP to immediately follow the 18x
response. Some clients do not support 18x with early media, while others require 18x
with early media (i.e., they cannot play ringback tone locally). These various
User's Manual
Mediant 1000B Gateway & SBC
504 Document #: LTRT-27034