Cisco SPA525G Administration Guide - Page 100

5 Configuring SIP, SPCP, and NAT Configuring SIP - The NTP timestamp used in the SR is a snapshot of the Cisco IP phone's local time, not the time reported by an NTP server. - If the Cisco IP phone receives a RR from the peer, it tries to compute the round trip delay and show it as the Call Round Trip Delay value in the Info section of the web GUI administration page. It can range from 0 to 255 seconds. Defaults to 0 (recommended). • No UDP Checksum-Select yes if you want the Cisco IP phone to calculate the UDP header checksum for SIP messages. Since this involves computation load, you should keep the default value (no) to disable it. • Symmetric RTP-Enable symmetric RTP operation. If enabled, 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) sends RTP to the destination as indicated in the inbound SDP. Defaults to no. • Stats in BYE-Determines whether the IP 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=,OS=,PR=,OR=,PL=,JI=,LA=,DU=,EN=,DE= Defaults to no. STEP 5 Click Submit All Changes. Configuring SDP Payload Types Configured dynamic payloads are used for outbound calls only when the Cisco IP phone presents an SDP offer. For inbound calls with an SDP offer, the phone follows the caller's assigned dynamic payload type. Cisco IP phones use the configured codec names in outbound SDP. For incoming SDP with standard payload types of 0-95, the Cisco IP phone ignores the codec names. For dynamic payload types, the Cisco IP phone identifies the codec by the configured codec names (comparison is case-sensitive). 98 Cisco SPA and Wireless IP Phone Administration Guide