12-02-2011 08:03 AM - edited 03-16-2019 08:21 AM
I've been carrying out some MLPP testing on CUCM 8.5, using a Cisco 2821 as an MGCP gateway. This gateway has an E1 connection from a Telco provider.
MLPP is configured up for a 999 call and I've busied out all channels on the E1 apart from channel 1.
I place the outbound call out to a mobile number, call is taking up the first channel. I then place a call to 999, the mobile call instantly drops and the 999 call is sent out as a preemption call but doesn't connect.
Here is the q931 debug from this..
Nov 30 15:37:24.333: ISDN Se0/1/0:15 Q931: TX -> SETUP pd = 8 callref = 0x0011
Sending Complete
Bearer Capability i = 0x8090A3
Standard = CCITT
Transfer Capability = Speech
Transfer Mode = Circuit
Transfer Rate = 64 kbit/s
Channel ID i = 0xA98381
Exclusive, Channel 1
Facility i = 0x91A115020168020119300D0A01040A010104050000000000
Calling Party Number i = 0x0081, '0241'
Plan:Unknown, Type:Unknown
Called Party Number i = 0x80, '07827342561'
Plan:Unknown, Type:Unknown
Nov 30 15:37:26.441: ISDN Se0/1/0:15 Q931: RX <- CALL_PROC pd = 8 callref = 0x8
011
Channel ID i = 0xA98381
Exclusive, Channel 1
Nov 30 15:37:32.389: ISDN Se0/1/0:15 Q931: RX <- ALERTING pd = 8 callref = 0x80
11
Nov 30 15:37:34.577: ISDN Se0/1/0:15 Q931: RX <- CONNECT pd = 8 callref = 0x801
1
Nov 30 15:37:34.581: ISDN Se0/1/0:15 Q931: TX -> CONNECT_ACK pd = 8 callref = 0
x0011
Nov 30 15:37:37.685: ISDN Se0/1/0:15 Q931: TX -> DISCONNECT pd = 8 callref = 0x
0011
Cause i = 0x8088 - Preemption
Facility i = 0x91A10902016902011A0A0101
Nov 30 15:37:37.705: ISDN Se0/1/0:15 Q931: RX <- RELEASE pd = 8 callref = 0x801
1
Cause i = 0x8088 - Preemption
Nov 30 15:37:37.733: ISDN Se0/1/0:15 Q931: TX -> RELEASE_COMP pd = 8 callref =
0x0011
Nov 30 15:37:37.753: ISDN Se0/1/0:15 Q931: TX -> SETUP pd = 8 callref = 0x0012
Sending Complete
Bearer Capability i = 0x8090A3
Standard = CCITT
Transfer Capability = Speech
Transfer Mode = Circuit
Transfer Rate = 64 kbit/s
Channel ID i = 0xA98381
Exclusive, Channel 1
Facility i = 0x91A11502016A020119300D0A01000A010104050000000000
Calling Party Number i = 0x0081, '0044'
Plan:Unknown, Type:Unknown
Called Party Number i = 0x80, '999'
Plan:Unknown, Type:Unknown
Nov 30 15:37:41.757: ISDN Se0/1/0:15 Q931: TX -> SETUP pd = 8 callref = 0x0012
Sending Complete
Bearer Capability i = 0x8090A3
Standard = CCITT
Transfer Capability = Speech
Transfer Mode = Circuit
Transfer Rate = 64 kbit/s
Channel ID i = 0xA98381
Exclusive, Channel 1
Facility i = 0x91A11502016A020119300D0A01000A010104050000000000
Calling Party Number i = 0x0081, '0044'
Plan:Unknown, Type:Unknown
Called Party Number i = 0x80, '999'
Plan:Unknown, Type:Unknown
Nov 30 15:37:45.769: ISDN Se0/1/0:15 Q931: TX -> RELEASE_COMP pd = 8 callref =
0x0012
Cause i = 0x80E6 - Recovery on timer expiry
--------------------------------------------------------------------------
We also have a seperate E1 link coming into the building that is provided by a different Telco provider and if I connect this into the gateway, the it works straight away....
I'm currently having a disupute with the original Telco provider about this, is there anything that needs to be done on the Telco side for MLPP calls to work ? Is it just a case that some dont provide this service ?
Anyone else in the UK had issues getting MLPP calls working over E1 ?
12-02-2011 08:11 AM
Hi,
Foound an old bug for this Cause code 0x80E6
CSCdu24355
When voice calls are placed using 2-stage dialing, the ISDN on the terminating gateway may disconnect the call with a 0x80E6 (Recovery on timer expiry) cause code if the call is terminated on a Foreign Exchange Station (FXS) endpoint.
Workaround: Enter the isdn t310 50000 configuration command on the serial interface of the terminating gateway.
Worth trying.
You may need to adjust the T310 timer on the CUCM system parameter
Regards
Alex
12-02-2011 08:48 AM
No, no joy. As stated, it works with a different E1 provider straight away..I think that timeout is pretty valid considering how long it waits for a response from the Telco after its transmitted the SETUP request twice.
12-04-2011 01:53 PM
Any ideas?
12-05-2011 03:23 AM
Ross,
As you said this could be a service provider issue.
I have searched for bugs for ISDN_PRI , MGCP & 2821 router.
I can not see anything that is relevant.
I can not see much even in the BT SIN
http://www.sinet.bt.com/369hv1p2.pdf
Other than that timers are supported
You seem to clear the original call OK
But immediatley send a new setup for 999
The SP never responds to your setup.
The SP would need a in line Q931 analyser like AURRA etc to veryfy what is going on.
You could try upgrading the IOS to the latest in your train.
What IOS are you running.
Regrds
Alex
12-05-2011 03:36 AM
Unfortunately the SP isn't being very helpful in this issue. I have a feeling that due to this SP not recognising the disconnect code for the original call - Cause i = 0x8088 - Preemption ( instead of the Normal Call Clearing code - 0x8090 ) then the line isn't cleared down correctly, for the 999 call to be routed out on their end ( even though the ISDN messages of the call clearing down seem complete ) Its the only thing different between a normal call being cut and a preemption call.
For info the IOS version on the gateway is 15.1(4)M
Could do with finding out if BT do something different to deal with Preemption than other SP's
12-06-2011 03:40 AM
Ross,
Which SP is the issue with.
Also may be try loading the latest IOS versions
15.1.4M2
or
regress to version 12
12.4.24T6
Regards
Alex
12-06-2011 05:03 AM
The issue is with Cable & Wireless/THUS, as stated, works fine with BT.
I'll try the different IOS levels and let you know. Cheers for taking time to reply Alex!
12-07-2011 09:05 AM
Alex,
Test calls failed regardless of the IOS running on the gateway, rolled back to 12.4 and took the latest 15.1 and no joy!
12-08-2011 01:22 AM
Ross,
It seems then the issue MUST be with C&W
Good luck
Regards
Alex
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