
Version 5.6 333 November 2008
SIP User's Manual 7. IP Telephony Capabilities
Below is an example of SIP messages implementing the X-Detect header:
Via: SIP/2.0/UDP 10.33.2.53;branch=z9hG4bKac5906
Max-Forwards: 70
CSeq: 1 INVITE
X- Detect: Request=CPT,FAX
SIP/2.0 200 OK
Via: SIP/2.0/UDP 10.33.2.53;branch=z9hG4bKac5906
CSeq: 1 INVITE
X- Detect: Response=CPT,FAX
Via: SIP/2.0/UDP 10.33.2.53;branch=z9hG4bKac5906
Max-Forwards: 70
CSeq: 1 INVITE
X- Detect: Response=CPT,FAX
Content-Type: Application/X-Detect
Content-Length: xxx
Type = CPT
Subtype = SIT
7.6 RTP Multiplexing (ThroughPacket)
The device supports a proprietary method to aggregate RTP streams from several channels
to reduce the bandwidth overhead caused by the attached Ethernet, IP, UDP, and RTP
headers, and to reduce the packet / data transmission rate. This option reduces the load on
network routers and can typically save 50% (e.g., for G.723) on IP bandwidth. RTP
Multiplexing (ThroughPacket™) is accomplished by aggregating payloads from several
channels that are sent to the same destination IP address into a single IP packet.
RTP multiplexing can be applied to the entire device (refer to ''Configuring the RTP / RTCP
Settings'' on page 73)
or to specific IP destinations using the IP Profile feature (refer to ''IP
Profile Settings'' on page 173).
To ena
ble RTP Multiplexing, set the parameter RemoteBaseUDPPort to a nonzero value.
Note that the value of RemoteBaseUDPPort on the local device must equal the value of
BaseUDPPort of the remote device. The device uses these parameters to identify and
distribute the payloads from the received multiplexed IP packet to the relevant channels.
In RTP Multiplexing mode, the device uses a single UDP port for all incoming multiplexed
packets and a different port for outgoing packets. These ports are configured using the
parameters L1L1ComplexTxUDPPort and L1L1ComplexRxUDPPort.
When RTP Multiplexing is used, call statistics aren’t available (since there is no RTCP
flow).
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