Dialogic IMG - How to Change T9 Timer in the SS7 ISDN User Part
Introduction:
T9 timer in the SS7 ISDN User Part is defined in Section 2.1.4.2), ITU-T Recommendation Q.764 (1997), Signalling System No. 7 – ISDN user part signalling procedures:
Upon receipt of an address complete message an intermediate national exchange will send the corresponding address complete message to the preceding exchange, and if this is the exchange controlling charging, the awaiting answer timer T9 is started. If timer (T9) expires, the connection is released and an indication is sent to the calling subscriber.
ITU Q.764 Table A.1 (Timers in the ISDN User Part) comments that T9 interval is specified in Rec. Q.118. Q.118 (09/97) and recommends T9 from 1.5 to 3 minutes. By default, Dialogic IMG 1010 Integrated Media Gateway sets T9 timer as 3 minutes.
This note describes a way to change the T9 timer on an IMG by using the raw API, which can change T9 timer for specified ISUP channels or channel groups.
Procedure:
In the IMG, the awaiting answer timer (T9) is PPL Timer id 5 in the PPL Component ISUP CPC (Call Processing Control - PPL id 0x0012),
The attached example changes the ISUP T9 timer to 2 minutes on ISUP CICs:
00 17 00 cf 00 01 01 01 02 0d 03 ss ss cc 0d 03 ee ee dd 00 12 01 05 2e e0
API Length: 0x0017
API 0x00CF - PPL Timer Configure
Reserved: 0x00
Sequence Number: 0x01
Node id: 0x01
AIB Address Method: 0x01 - Range
Number of AEs to follow - 0x02
Address Element 1 (0x0D), Length 0x03, defines the Starting Logical Channel - ss ss cc (ss ss is starting logical span, cc is starting logical channel)
Address Element 1 (0x0D), Length 0x03, defines the Ending Logical Channel - ee ee dd (ee ee is ending logical span, dd is ending logical channel)
PPL id: 0x0012 ISUP CPC (Call Processing Control)
PPL Timer Type: 1
PPL Timer ID: 5 - ISUP T9
PPL Timer Value (10ms unit): 0x2ee0 (12000) = 120s
In addtion to ISUP T9 timer change, an internal timer (L3 connect wait) needs to be changed to 1 second less than ISUP T9 timer; this timer is PPL Timer id 5 in the PPL Component L4 CH (L4 Channel - PPL id 0x0061),
00 17 00 cf 00 01 01 01 02 0d 03 ss ss cc 0d 03 ee ee dd 00 61 01 05 2e 7c
API Length: 0x0017
API 0x00CF - PPL Timer Configure
Reserved: 0x00
Sequence Number: 0x01
Node id: 0x01
AIB Address Method: 0x01 - Range
Number of AEs to follow - 0x02
Address Element 1 (0x0D), Length 0x03, defines the Starting Logical Channel - ss ss cc (ss ss is starting logical span, cc is starting logical channel)
Address Element 1 (0x0D), Length 0x03, defines the Ending Logical Channel - ee ee dd (ee ee is ending logical span, dd is ending logical channel)
PPL id: 0x0061 L4CH
PPL Timer Type: 1
PPL Timer ID: 5 - L3 Connect Wait
PPL Timer Value (10ms unit): 0x2e7c (11900) = 119s
Steps to find the logical span of SS7 CICs (physical span) to be configured:
Telnet to the IMG 1010
Type d to display Advanced Menu
Type k to display assigned span
Advanced Debug> k
Assigned Spans
PhyID LogID Profile State Timing
(comp.if.grp) def/act host/act
------------ ------------- ------- -------- ------
(00.01.00) 0x003d( 61) E1 / E1 INS/INS REF2*
(01.00.00) 0x0020( 32) E1 / E1 INS/INS
(01.01.00) 0x0021( 33) E1 / E1 INS/INS
(01.02.00) 0x0022( 34) E1 / E1 INS/INS
(01.03.00) 0x0023( 35) E1 / E1 INS/INS
(01.04.00) 0x0024( 36) E1 / E1 INS/INS
(01.05.00) 0x0025( 37) E1 / E1 INS/INS
(01.06.00) 0x0026( 38) E1 / E1 INS/INS
(01.07.00) 0x0027( 39) E1 / E1 INS/INS
(01.08.00) 0x0028( 40) E1 / E1 INS/INS
(01.10.00) 0x002a( 42) E1 / E1 INS/AIS
(01.14.00) 0x002e( 46) E1 / E1 INS/LOS
comp '0' : the E1 span is configured on Signaling Interface Span
comp '1' : the E1 span is configured on Bearer Interface Span
if : offset of E1 span on Signaling/Bearer interface
Product List
Dialogic IMG 1010 Integrated Media Gateway
Glossary of Acronyms / Terms
ISUP - ISDN User Part
ISUP CIC - Circuit Identification Code