PRI Call dropping

[KurpeusLondon]

Hi guys,

A user reported call droping issues while calling three different numbers. I can't find anything wrong with our PRI and based on the following info I thing the issue isn't on my side

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:48:58 2011 Call_Id:80d8
ISDN VDsu-1 Mod 1 Port 1
Outgoing: Channel: 3 Called Num: XXXXXXX9933

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:49:00 2011 Call_Id:80d8
ISDN VDsu-1 Mod 1 Port 1
Incoming: Cause: Normal, unspecified

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:49:00 2011 Call_Id:80d8
ISDN VDsu-1 Mod 1 Port 1
Outgoing: Cause: Normal, unspecified



ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:49:15 2011 Call_Id:80d9
ISDN VDsu-1 Mod 1 Port 1
Outgoing: Channel: 3 Called Num: XXXXXXX9933

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:49:17 2011 Call_Id:80d9
ISDN VDsu-1 Mod 1 Port 1
Incoming: Cause: Normal, unspecified

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:49:17 2011 Call_Id:80d9
ISDN VDsu-1 Mod 1 Port 1
Outgoing: Cause: Normal, unspecified



ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:51:10 2011 Call_Id:80db
ISDN VDsu-1 Mod 1 Port 1
Outgoing: Channel: 1 Called Num: XXXXXXX1451

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:51:12 2011 Call_Id:80db
ISDN VDsu-1 Mod 1 Port 1
Incoming: Cause: Unallocated (unassigned) number

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:51:12 2011 Call_Id:80db
ISDN VDsu-1 Mod 1 Port 1
Outgoing: Cause: Unallocated (unassigned) number



ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:51:21 2011 Call_Id:80dc
ISDN VDsu-1 Mod 1 Port 1
Outgoing: Channel: 1 Called Num: XXXXXXX1451

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:51:22 2011 Call_Id:80dc
ISDN VDsu-1 Mod 1 Port 1
Incoming: Cause: Unallocated (unassigned) number

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:51:23 2011 Call_Id:80dc
ISDN VDsu-1 Mod 1 Port 1
Outgoing: Cause: Unallocated (unassigned) number


These two phone numbers were going to different code area but I wouldn’t be surprised if they are physically going to the same destination. In the meantime I had others call not experiencing any issue.

I check few statistics about my PRI. It looks fine but there are few MTAlarms messages bellow I don't fully understand:

MTALARMS (built Mar 25 2010 @ 17:57:53)
-- current alarm states on link 0, VDSU 0:

Alarm name severity state // Alarm name severity state

Loss_of_Signal Info clear // Red_Alarm Info clear

Yellow_Alarm Major clear // FDL_PLB Info clear

Data_Link_Failure Info clear // Power_On_Reset Info clear

Initialize_Time Info clear // Density_Violation Info clear

CSU_Loopback Info clear // Out_Signal_Loss Info clear

In_Signal_Loss Info clear // Frame_Align_Loss Info clear

Rmt_Frame_Align_Loss Info clear // Error_Rate Info clear

Sync_Cntrl_1 Info clear // Sync_Cntrl_2 Info clear

Trigger_Failure Info clear // Optioning_Failure Info clear

INVALID Info clear // No_Timing_Interface Info clear

Dchannel_Failure Critical clear
Current_state: SX2K_PASS, request timer is NOT SET,
The intitial link status has been received.
We have NOT forced the D-channel down.
The force D-channel up timer has NOT been set.



ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:42:59 2011 MTALARMS -- get alert 1 state=1.

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:42:59 2011 MTALARMS -- get alert 2 state=1.

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:42:59 2011 MTALARMS -- get alert 1 state=1.

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:42:59 2011 MTALARMS -- get alert 2 state=1.

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:42:59 2011 MTALARMS -- get alert 0 state=1.

ISDN VDsu-1 Mod 1 Port 1 - WED MAR 02 09:42:59 2011 MTALARMS -- get alert 0 state=1.

Universal E1 3 1 2 1
Link is Available
duty bit
cycle framing error
Time (%) losses slips rate
------------------------------------------------
9:42 100 0 0 0
9:00 100 0 0 0
8:00 100 0 0 0
7:00 100 0 0 0
6:00 100 0 0 0
5:00 100 0 0 0
4:00 100 0 0 0
3:00 100 0 0 0
2:00 100 0 0 0
1:00 100 0 0 0
0:00 100 0 0 0
23:00 100 0 0 0
22:00 100 0 0 0
21:00 100 0 0 0
20:00 100 0 0 0
19:00 100 0 0 0
18:00 100 0 0 0
17:00 100 0 0 0
16:00 100 0 0 0
15:00 100 0 0 0
14:00 100 0 0 0
13:00 100 0 0 0
12:00 100 0 0 0
11:00 100 0 0 0
10:00 100 0 0 0
------------------------------------------------


PRI Logical link number: 1
Layer 1 Status: GREEN
Layer 2 Status: UP
Interface Activated: TRUE

Location | Device | State | Owner | ID |Status
----------------------------------------------------------------------------
3 1 2 1 1| Universal E1 | Busy |Call Proc|6 254|Wait
3 1 2 1 2| Universal E1 | Busy |Call Proc|8 21E|Wait
3 1 2 1 3| Universal E1 | Idle | | |
3 1 2 1 4| Universal E1 | Idle | | |
3 1 2 1 5| Universal E1 | Idle | | |
3 1 2 1 6| Universal E1 | Idle | | |
3 1 2 1 7| Universal E1 | Unassigned | | |
3 1 2 1 8| Universal E1 | Unassigned | | |
3 1 2 1 9| Universal E1 | Unassigned | | |
3 1 2 1 10| Universal E1 | Unassigned | | |
3 1 2 1 11| Universal E1 | Unassigned | | |
3 1 2 1 12| Universal E1 | Unassigned | | |
3 1 2 1 13| Universal E1 | Unassigned | | |
3 1 2 1 14| Universal E1 | Unassigned | | |
3 1 2 1 15| Universal E1 | Unassigned | | |
3 1 2 1 16| Universal E1 | Unassigned | | |
3 1 2 1 17| Universal E1 | Unassigned | | |
3 1 2 1 18| Universal E1 | Unassigned | | |
3 1 2 1 19| Universal E1 | Unassigned | | |
3 1 2 1 20| Universal E1 | Unassigned | | |
3 1 2 1 21| Universal E1 | Unassigned | | |
3 1 2 1 22| Universal E1 | Unassigned | | |
3 1 2 1 23| Universal E1 | Unassigned | | |
3 1 2 1 24| Universal E1 | Unassigned | | |
3 1 2 1 25| Universal E1 | Unassigned | | |
3 1 2 1 26| Universal E1 | Unassigned | | |
3 1 2 1 27| Universal E1 | Unassigned | | |
3 1 2 1 28| Universal E1 | Unassigned | | |
3 1 2 1 29| Universal E1 | Unassigned | | |
3 1 2 1 30| Universal E1 | Unassigned | | |
----------------------------------------------------------------------------


| Sync Source | Sync Source
No. | Location | Status
-----+------------------+------------------
1 | 3 1 2 1 | sync source

Time | | single | phase | control |
start end | act | hits | shifts| range % | sync sources used
------------+-----+--------+-------+---------+------------------
10:30 10:52 | ACT | 0 | 0 | 93 - 93 | 1
11:29 10:30 | ACT | 0 | 0 | 93 - 93 | 1
10:29 11:29 | ACT | 0 | 0 | 93 - 93 | 1

The system is an ICP3300 CX II running MCD4.1 SP1


Thanks,

 

[Supernova99]

looks to me like you have calls coming in on unassigned channels
Can you assign all the channels as this has been known to cause issues with signalling.
You do not have to add any of these to the outgoing trunk group just assign trunk numbers to all the unassigned channels.

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[KurpeusLondon]

Hmm you are right. I had to rebuild my controller last week and I assigned 6 channels only. I've just tested and we subscribed for 8 Channels.

8 Channels in my trunk group, all the others were given a trunk number. I'll see if I have these MTALARMS anymore.


Another point, when I use the individual trunk access feature, i can get the first two channels (3121 and 3122) but not the others ones. When I check what channels are being used by phone calls, all 8 of them are used (circular trunk group) so why can't I used the individual trunk access for trunk group 3123 -> 3128 ? They all use the same COS !

 

[Supernova99]

Not sure what you mean by being used.
If you use individual trunk access on a PRI link you will either get silence (siezed) or busy.
Have you got a numbr clash somewhere?

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[KurpeusLondon]

Well, I have 8 channels subscribed, all group in the same trunk group. (Trunk 3121 to 3128) The hunt made is set to circular, so each time I make a phone call, a new trunk is used. This proves me I can use any of these channels. What I don't get is why do I have an error displayed on my phone when I use the individual trunk access on trunks other than 3121 and 3122. I should be able to test them the same way since they all use the same COS.

To keep things simple, I gave my trunk the same number as my circuit

for example.

Cabinet 3 Self 1 Slot 2 circuit 1 is assigned the trunk number 3121
Cabinet 3 Self 1 Slot 2 circuit 2 is assigned the trunk number 3122
etc, ...

 

[Supernova99]

Check to see if you have a number clash
Try locate number plus the FAC plus the trunk number
e.g. LOCATE NUMBER **23123 from the maintenance commands

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