Cisco IP Telephony Troubleshooting Guide for Cisco CallManager Release 3.0(1)
© 2000 Cisco Systems, Inc.
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The callref uses a different value for the first digit (to differentiate between TX and RX) and the
second value is the same (SETUP had a 0 for the last digit and CONNECT_ACK also has a 0).
The router is completely dependent upon the PSTN or PBX to assign a Bearer channel (B-
channel). If the PSTN or PBX doesn't assign a channel to the router, the call won't be routed. In
our case, a CONNECT message is received from the switch with the same reference number as
was received for ALERTING (0x800B). Finally, you can see the exchange of the
DISCONNECT message followed by RELEASE and RELEASE _COMP messages as the call is
being disconnected. RELEASE_COMP messages are followed by a cause ID for the call
rejection. The cause ID is a hex value. The meaning of the cause can be found by decoding the
hex value and following up with your provider.
*Mar 1 225209.694 ISDN Se115 TX -> SETUP pd = 8 callref = 0x000B
*Mar 1 225209.694 Bearer Capability i = 0x8090A3
*Mar 1 225209.694 Channel ID i = 0xA98381
*Mar 1 225209.694 Calling Party Number i = 0x2183, ’1001'
*Mar 1 225209.694 Called Party Number i = 0x80, ’3333'
*Mar 1 225209.982 ISDN Se115 RX <- ALERTING pd = 8 callref = 0x800B
*Mar 1 225209.982 Channel ID i = 0xA98381
*Mar 1 225210.674 ISDN Se115 RX <- CONNECT pd = 8 callref = 0x800B
*Mar 1 225210.678 ISDN Se115 TX -> CONNECT_ACK pd = 8 callref = 0x000B
*Mar 1 225215.058 ISDN Se115 RX <- DISCONNECT pd = 8 callref = 0x800B
*Mar 1 225215.058 Cause i = 0x8090 - Normal call clearing 225217 %ISDN-6
DISCONNECT Int S10 disconnected from unknown , call lasted 4 sec
*Mar 1 225215.058 ISDN Se115 TX -> RELEASE pd = 8 callref = 0x000B
*Mar 1 225215.082 ISDN Se115 RX <- RELEASE_COMP pd = 8 callref = 0x800B
*Mar 1 225215.082 Cause i = 0x829F - Normal, unspecified or Special intercept, call blocked group
restriction
Cisco IOS Gateway with T1/CAS Interface
As explained earlier, there are two types of calls going through the Cisco IOS Gateways: the
Cisco IOS Gateway interface to the PSTN or PBX with either T1/CAS or T1/PRI interfaces. The
following are the debug outputs when the Cisco IOS Gateways has T1/CAS interface. The
“debug cas” on the Cisco IOS Gateway has been turned on.
The following debug message shows that the Cisco IOS Gateway is sending an off-hook signal
to the switch.
Apr 5 17:58:21.727: from NEAT(0): (0/15): Tx LOOP_CLOSURE (ABCD=1111)
The following debug message indicates the switch is sending wink after receiving the loop
closure signal from the Cisco IOS Gateway.
Apr 5 17:58:21.859: from NEAT(0): (0/15): Rx LOOP_CLOSURE (ABCD=1111)
Apr 5 17:58:22.083: from NEAT(0): (0/15): Rx LOOP_OPEN (ABCD=0000)
The following debug message indicates the Cisco IOS Gateway is going off-hook.
Apr 5 17:58:23.499: from NEAT(0): (0/15): Rx LOOP_CLOSURE (ABCD=1111)
