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New Member

MLPP Calls over E1

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 ?

Everyone's tags (3)
9 REPLIES
Green

Re: MLPP Calls over E1

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

Regards, Alex. Please rate useful posts.
New Member

MLPP Calls over E1

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.

New Member

Re: MLPP Calls over E1

Any ideas?

Green

Re: MLPP Calls over E1

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

Regards, Alex. Please rate useful posts.
New Member

Re: MLPP Calls over E1

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

Green

Re: MLPP Calls over E1

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

Regards, Alex. Please rate useful posts.
New Member

Re: MLPP Calls over E1

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!

New Member

Re: MLPP Calls over E1

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!

Green

Re: MLPP Calls over E1

Ross,

It seems then the issue MUST be with C&W

Good luck

Regards

Alex

Regards, Alex. Please rate useful posts.
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