ISUP User Part Timers
From TBwiki
All timer values must be expressed in milliseconds. Those timers are defined as follows:
| Timer | Description |
|---|---|
| T1 Timer | RELEASE message sent. Terminated normally at the receipt of an RLC message. Typical values are 15 to 60 seconds. |
| T2 Timer | SUSPEND message receive by controlling exchange. Terminated normally when RESUME (user) is received at the controlling exchange. Typical value is 3 minutes. |
| T5 Timer | INITIAL RELEASE message sent. Terminated normally at the receipt of the RLC message. Typical values are 5 to 15 minutes. |
| T6 Timer | SUSPEND (network) received by controlling exchange. Terminated normally at the receipt of RESUME (network) or RELEASE. Typical value is 1 second (SPIROU : 60-120 seconds) |
| T7 Timer | LATEST ADDRESS message sent. Terminated normally when the condition for normal release of address and routing information is met. Typical values are 20 to 30 seconds. |
| T8 Timer | INITIAL ADDRESS message received by incoming international exchange. Typical values are 10 to 15 seconds. |
| T9 Timer | LATEST ADDRESS message sent by the outgoing international exchange. Terminated normally at the receipt of answer. Typical values are 90 to 180 seconds. |
| T27 Timer | Waiting for continuity rechecks. Terminated normally when the CONTINUITY CHECK REQUEST message is received. . Typical value is 4 minutes. |
| T31 Timer | Release of ISUP signaling connection based on connection oriented SCCP. Call reference is frozen during this period and is reusable after the timer expiry. Typical values are more than 6 minutes. |
| T33 Timer | Information request sent. Terminated normally when INF message is received. Typical values are 12 to 15 seconds. |
| T34 Timer | Waiting for continuity after rechecks (ANSI88, ANSI92 and Telcordia). For the ITU segmentation timer, see un32T36Timer. Typical values are 2 to 4 seconds. |
| T36 Timer | Awaiting for another segmented message. For ITU-T, ETSI and FTZ, this timer substitute for the T34 (ANSI). Typical values are 10 to 15 seconds. |
| CCr Timer | Continuity recheck timer. Typical value is 20 seconds. |
| Ex Timer | Exit to be sent (ANSI and Telcordia). The values are dependent upon the network. |
| CCR Timer | Awaiting LPA message after having sent CCR (ANSI88, ANSI92 and Telcordia). Typical value is 2 seconds. |
| CRM Timer | Circuit reservation sent, waiting for reservation acknowledge (ANSI92 and Telcordia). Typical values are from 3 to 4 seconds. |
| CRA Timer | Circuit reservation acknowledge sent, waiting for IAM (ANSI92 and Telcordia). Terminated normally when IAM is received.. Typical value is 10 seconds. |
| ECT Timer | Explicit call transfer, waiting for LOOP PREVENTION RESPONSE message (ETSI, ETSI V3 and ITU97). Typical value is 1 second. |
| RELRSP Timer | Waiting for release response timer. It is used to account for loss of release response primitive. Typical values are system-dependent. |
| FNLRELRSP Timer | Waiting for release response timer. It is used to account for the loss of release response primitive. If the release response from the host application is not received before the expiry of this timer, circuit reset is locally initiated by the ISUP userpart. Typical values are system-dependent. |
NOTE: The following timers are not required for the UK: T8, T27, T31, T36. The value of T33 is 5-15s. If Timer (T33) matures, the call shall continue in the normal way.
