[cisco-voip] Calls from the PSTN getting 'No circuit/channel available'

pedro marques pmarques74 at gmail.com
Thu May 10 10:31:03 EDT 2007


Hi,

I have a CCM running 4.2 connecting through MGCP to a 2821 Gateway.
After some debugging and traces enabled on the CCM I noticed that the calls
that are getting disconnected from the PSTN all fall in the first 5 channels
of the E1 PRI.

These are the relevant commands on the 2821:

controller E1 0/0/0
 pri-group timeslots 1-16 service mgcp
!
interface Serial0/0/0:15
 no ip address
 isdn switch-type primary-net5
 isdn incoming-voice voice
 isdn bind-l3 ccm-manager
 isdn bchan-number-order ascending
 no cdp enable
!
ccm-manager mgcp
ccm-manager config server <CCM ip address>
!
mgcp
mgcp call-agent <CCM ip address> service-type mgcp version 0.1
mgcp dtmf-relay voip codec all mode out-of-band
mgcp package-capability rtp-package
mgcp default-package line-package
mgcp sdp simple
!
mgcp profile default

These are two snippets from a 'debug isdn q931':

*May 10 11:32:02.582: ISDN Se0/0/0:15 Q931: RX <- SETUP pd = 8  callref =
0x007F
        Sending Complete
        Bearer Capability i = 0x9090A3
                Standard = CCITT
                Transfer Capability = 3.1kHz Audio
                Transfer Mode = Circuit
                Transfer Rate = 64 kbit/s
        Channel ID i = 0xA18384
                Preferred, Channel 4
        Progress Ind i = 0x8183 - Origination address is non-ISDN
        Calling Party Number i = 0x0083, 'calling party number'
                Plan:Unknown, Type:Unknown
        Called Party Number i = 0x81, 'called party number'
                Plan:ISDN, Type:Unknown
*May 10 11:32:02.602: ISDN Se0/0/0:15 Q931: TX -> CALL_PROC pd = 8  callref
= 0x807F
        Channel ID i = 0xA98384
                Exclusive, Channel 4
*May 10 11:32:02.602: ISDN Se0/0/0:15 Q931: TX -> DISCONNECT pd = 8  callref
= 0x807F
        Cause i = 0x80A2 - No circuit/channel available
*May 10 11:32:02.790: ISDN Se0/0/0:15 Q931: RX <- RELEASE pd = 8  callref =
0x007F
*May 10 11:32:02.802: ISDN Se0/0/0:15 Q931: TX -> RELEASE_COMP pd = 8
callref = 0x807F


*May 10 11:33:35.062: ISDN Se0/0/0:15 Q931: RX <- SETUP pd = 8  callref =
0x0057
        Sending Complete
        Bearer Capability i = 0x9090A3
                Standard = CCITT
                Transfer Capability = 3.1kHz Audio
                Transfer Mode = Circuit
                Transfer Rate = 64 kbit/s
        Channel ID i = 0xA18383
                Preferred, Channel 3
        Progress Ind i = 0x8283 - Origination address is non-ISDN
        Calling Party Number i = 0x0083, 'calling party number'
                Plan:Unknown, Type:Unknown
        Called Party Number i = 0x81, 'called party number'
                Plan:ISDN, Type:Unknown
*May 10 11:33:35.086: ISDN Se0/0/0:15 Q931: TX -> CALL_PROC pd = 8  callref
= 0x8057
        Channel ID i = 0xA98383
                Exclusive, Channel 3
*May 10 11:33:35.086: ISDN Se0/0/0:15 Q931: TX -> DISCONNECT pd = 8  callref
= 0x8057
        Cause i = 0x80A2 - No circuit/channel available

In attachment I include a file (copy of ccm00000065.txt) that has the
relevant information taken from a CCM Trace log and run through Voice Log
Translator.

With all this information I went to check the MGCP Gateway configuration in
CCMAdmin. Some of the configuration elements included on the E1 endpoint
configuration page and that are somewhat confusing me (mind you that this is
an inherited configuration) are as follows:

Channel Selection Order: BOTTOM_UP (since the configuration on the gateway's
interface Serial0/0/0:15 is for bchan-number-order ascending, shouldn't
these parameters match by using the TOP_DOWN option?)

Channel IE Type: Use Number When 1B (This is an option that I don't fully
understand. Any help on this would be appreciated. But to what I understand,
and since the E1 PRI configuration is only used for half a primary (15
channels) shouldn't this parameter be set to 'Timeslot Number'?)

TIA


-- 
Pedro Miguel Marques
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05/10/2007 12:26:07.800	Send	10.105.0.20	Q.931	DISCONNECT	0x800D	S0/SU0/DS1-0/1
Message Header
08 02 80 0D 45
 -- DISCONNECT, pd = 8, callref = 0x800D

Information Element(s)
 08 02 80 A2
 -- Cause i = 0x0800A2 - No channel available 

Entire Message:
0010: 08 02 80 0D 45 08 02 80 A2
--------------------------------------------------------------------

05/10/2007 12:26:27.863	Send	10.105.0.20	Q.931	DISCONNECT	0x8036	S0/SU0/DS1-0/3
Message Header
08 02 80 36 45
 -- DISCONNECT, pd = 8, callref = 0x8036

Information Element(s)
 08 02 80 A2
 -- Cause i = 0x0800A2 - No channel available 

Entire Message:
0010: 08 02 80 36 45 08 02 80 A2
--------------------------------------------------------------------

05/10/2007 12:27:48.615	Send	10.105.0.20	Q.931	DISCONNECT	0x807F	S0/SU0/DS1-0/4
Message Header
08 02 80 7F 45
 -- DISCONNECT, pd = 8, callref = 0x807F

Information Element(s)
 08 02 80 A2
 -- Cause i = 0x0800A2 - No channel available 

Entire Message:
0010: 08 02 80 7F 45 08 02 80 A2
--------------------------------------------------------------------

05/10/2007 12:28:04.100	Send	10.105.0.20	Q.931	DISCONNECT	0x800B	S0/SU0/DS1-0/5
Message Header
08 02 80 0B 45
 -- DISCONNECT, pd = 8, callref = 0x800B

Information Element(s)
 08 02 80 A2
 -- Cause i = 0x0800A2 - No channel available 

Entire Message:
0010: 08 02 80 0B 45 08 02 80 A2
--------------------------------------------------------------------


05/10/2007 12:28:27.179	Send	10.105.0.20	Q.931	DISCONNECT	0x8001	S0/SU0/DS1-0/2
Message Header
08 02 80 01 45
 -- DISCONNECT, pd = 8, callref = 0x8001

Information Element(s)
 08 02 80 A2
 -- Cause i = 0x0800A2 - No channel available 

Entire Message:
0010: 08 02 80 01 45 08 02 80 A2
--------------------------------------------------------------------

05/10/2007 12:28:29.522	Send	10.105.0.20	Q.931	DISCONNECT	0x8069	S0/SU0/DS1-0/2
Message Header
08 02 80 69 45
 -- DISCONNECT, pd = 8, callref = 0x8069

Information Element(s)
 08 02 80 A2
 -- Cause i = 0x0800A2 - No channel available 

Entire Message:
0010: 08 02 80 69 45 08 02 80 A2
--------------------------------------------------------------------

05/10/2007 12:28:37.304	Send	10.105.0.20	Q.931	DISCONNECT	0x8075	S0/SU0/DS1-0/2
Message Header
08 02 80 75 45
 -- DISCONNECT, pd = 8, callref = 0x8075

Information Element(s)
 08 02 80 A2
 -- Cause i = 0x0800A2 - No channel available 

Entire Message:
0010: 08 02 80 75 45 08 02 80 A2
--------------------------------------------------------------------



05/10/2007 12:29:21.102	Send	10.105.0.20	Q.931	DISCONNECT	0x8057	S0/SU0/DS1-0/3
Message Header
08 02 80 57 45
 -- DISCONNECT, pd = 8, callref = 0x8057

Information Element(s)
 08 02 80 A2
 -- Cause i = 0x0800A2 - No channel available 

Entire Message:
0010: 08 02 80 57 45 08 02 80 A2
--------------------------------------------------------------------


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