QSIG-ISDN Timers

T301

Started when an ISDN call enters the alerting state (i.e.receive an ALERT message) and if it expires clears the call. Prevents the call from ringing forever.

T302

Specifies the time between digits in overlapped dialing.  If it expires it is assumed all digits have been received.

T303

Specifies the time after sending a ISDN SETUP message to wait for a response. First expiration will resend the SETUP and second expiration will fail the call.

T305

Specifies the time to wait after sending an ISDN DISCONNECT message to wait for the RELEASE message response. If it expires we then send an ISDN RELEASE message.

T308

Specifies the time to wait after sending an ISDN RELEASE message to wait for the RELEASE COMPLETE message response. First expiration will resend the RELEASE message and second expiration will send a RELEASE COMPLETE message.

T309

Specifies the time to wait after the D channel goes down for B channels with calls in the active state to wait for the D channel to come back up. If it expires and the D channel has not come back up the call on the B channel is cleared.

T310

Specifies the time to wait after receiving a CALL PROCEEDING message to wait for some form of call progress, i.e. a PROGRESS, ALERT or CONNECT message. If it expires the call is cleared.

T313

Specifies the time for user side ISDN to wait after sending a CONNECT message to wait for the CONNECT ACKNOWLEDGE message. If it expires then the call is cleared.

T314

Specifies the time to wait between SEGMENT messages for segmented message support in QSIG. If it expires all previously received SEGMENT messages are discarded and ignored.

T316

Specifies the time to wait after sending a RESTART message to wait for the RESTART ACKNOWLEDGE. First expiration will resend the RESTART message and second expiration will put the channel in local maintenance state for protocols that support service messaging. For protocols that don't support service messaging channel will be returned to the idle state.

T322

Specifies the time to wait after sending a STATUS ENQUIRY message to get the STATUS message response. First expiration will resent the STATUS ENQUIRY message and second expiration will clear an active call. Only started if T309 doesn't expire and the D channel comes back up before T309 expires on B channels with active calls.

T3M1(T323)

Specifies the time to wait after sending a SERVICE message to get the SERVICE ACKNOWLEDGE response. If it expires the SERVICE message will be resent. For NI-2 this is a maximum of 3 attempts before leaving the B channel in the state it was before and not changing its state.