Network Deployment (Distributed operating systems), v8.0 > Reference > Developer detailed usage information
SIP timer summary
Request for Comments (RFC) 3261, "SIP: SIP," specifies various timers that SIP uses.
Summary of SIP timers summarizes for each SIP timer the default value, the section of RFC 3261 that describes the timer, and the meaning of the timer.
Summary of SIP timers.
This table lists a summary of SIP timers.
Timer Default value Section Meaning T1 500 ms 17.1.1.1 Round-trip time (RTT) estimate T2 4 sec. 17.1.2.2 Maximum retransmission interval for non-INVITE requests and INVITE responses T4 5 sec. 17.1.2.2 Maximum duration that a message can remain in the network Timer A initially T1 17.1.1.2 INVITE request retransmission interval, for UDP only Timer B 64*T1 17.1.1.2 INVITE transaction timeout timer Timer C > 3 min. 16.6 bullet 11 Proxy INVITE transaction timeout Timer D > 32 sec. for UDP 17.1.1.2 Wait time for response retransmissions 0 sec. for TCP and SCTP Timer E initially T1 17.1.2.2 Non-INVITE request retransmission interval, UDP only Timer F 64*T1 17.1.2.2 Non-INVITE transaction timeout timer Timer G initially T1 17.2.1 INVITE response retransmission interval Timer H 64*T1 17.2.1 Wait time for ACK receipt Timer I T4 for UDP 17.2.1 Wait time for ACK retransmissions 0 sec. for TCP and SCTP Timer J 64*T1 for UDP 17.2.2 Wait time for retransmissions of non-INVITE requests 0 sec. for TCP and SCTP Timer K T4 for UDP 17.1.2.2 Wait time for response retransmissions 0 sec. for TCP and SCTP
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