+

Search Tips   |   Advanced Search

SIP timer summary


Request for Comments (RFC) 3261, "SIP: Session Initiation Protocol," 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.


Table 1. 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





 

Related tasks


Browse all SIP topics
Use Session Initiation Protocol to provide multimedia and interactive services

 

Related


SIP proxy server custom properties