Linksys SPA921-NA Administrator's Manual page 112

SIP Tab
RTCP Tx Interval
No UDP Checksum
Symmetric RTP
Stats In BYE
Linksys 900 Series IP Phone Administrator Guide
5-14
Interval for sending out RTCP sender reports on an active connection. It can range
from 0 to 255 seconds. During an active connection, the 900 Series phone can be
programmed to send out compound RTCP packet on the connection. Each
compound RTP packet except the last one contains a SR (Sender Report) and a
SDES.(Source Description). The last RTCP packet contains an additional BYE
packet. Each SR except the last one contains exactly 1 RR (Receiver Report); the
last SR carries no RR. The SDES contains CNAME, NAME, and TOOL
identifiers. The CNAME is set to <User ID>@<Proxy>, NAME is set to <Display
Name> (or Anonymous if user blocks caller ID), and TOOL is set to the
Vendor/Hardware-platform-software-version (such as Linksys/900 Series
phone-1.0.31(b)). The NTP timestamp used in the SR is a snapshot of the 900
Series phone's local time, not the time reported by an NTP server. If the 900
Series phone receives a RR from the peer, it attempts to compute the round trip
delay and show it as the <Call Round Trip Delay> value (ms) in the Info section
of 900 Series phone web page.
The default is 0.
Select yes if you want the 900 Series phone to calculate the UDP header checksum
for SIP messages. Otherwise, select no.
The default is no.
Enable symmetric RTP operation. If enabled, the SPA3102 sends RTP packets to
the source address and port of the last received valid inbound RTP packet. If
disabled (or before the first RTP packet arrives) the SPA3102 sends RTP to the
destination as indicated in the inbound SDP.
The default is yes.
Determines whether the 900 Series phone includes the P-RTP-Stat header or
response to a BYE message. The header contains the RTP statistics of the current
call. Select yes or no from the drop-down menu. The format of the P-RTP-Stat
header is:
P-RTP-State: PS=<packets sent>,OS=<octets sent>,PR=<packets
received>,OR=<octets received>,PL=<packets lost>,JI=<jitter in
ms>,LA=<delay in ms>,DU=<call duration in
s>,EN=<encoder>,DE=<decoder>.
The default is no.
Chapter 5 SPA900 Series Phone Field Reference
Document Version 3.0