Welltech LP-389 v.1.06 Administrator Guide - Manual (Page 13)

SIP Timer Settings: (for advance user only)
VOIP Setting > SIP Time
Parameter Description:
z SIP T1(msec): T1 determines several timers as defined in RFC3261. For
example, when an unreliable transport protocol is used, a Client Invite
transaction retransmits requests at an interval that start at T1 seconds
and doubles after every retransmission. A Client General transaction
retransmits requests at an interval that starts at T1 and doubles until it
reaches T2. (Default Value: 500ms) **
z SIP T2(msec): Determines the maximum retransmission interval as
defined in RFC3261. For example, when an unreliable transport protocol
is used, general requests are retransmitted at an interval which starts at
T1 and doubles until reaches T2. If a provisional response is received,
retransmission continue but at an interval of T2. (Default Value: 4000ms)
**
z SIP T4(msec): T4 represents the amount of time the network takes to
clear message between client and server transactions as defined in
RFC3261. For example, when working with an unreliable transport
protocol, T4 determines the time that UAS waits after receiving an ACK
message and before terminating the transaction. (Default Value: 5000)
**
z Invite Linger Timer: After sending an ACK for an INVITE final response,
a client cannot be sure that the server has received the ACK message.
The client should be able to
z retransmit the ACK upon receiving retransmissions of the final response
for this timer. This timer is also used when a 2xx response is sent for an
incoming Invite. In this case, the ACK is not part of the Invite
transaction.
z General Linger Timer: After a UAS sends a final response, the UAS
cannot be sure that the client has received the response message. The
UAS should be able to retransmit the
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