Something I found on the Web apparently from Avaya which outlines steps in toubleshooting the Merlin Magix PBX PRI problems.  I found it helpful in one case.  The scenarion says "D-channel inoperative", but we had the D-channel up and experienced a number of Layer 2 problems.  These steps (a couple of steps here) resolved the problem:

PRI TROUBLESHOOTING- D Channel Inoperative

1)    Check Permanent alarm table for any other T carrier related alarms (i.e., DS1 loss of  Signal). If present trouble shoot those alarms. (See Errors below)

2) Verify the status of the network and the DTE on the CSUs  LEDs. Troubleshoot
accordingly if either side shows a problem . (On 3160/3164 CSU, verify that the LEDs are assigned to DTE.

3) Verify that the CSU channels are mapped and Programmed for DATA
4) Verify that the CO (Central Office) switch selection in the PRI programming is correct
i.e., B8ZS/ESF

5) Verify that the Magix TEI is set for 0 ( Lines/Trunks>PRI>Protocol>TEI.)

6) Demand Test the 100d module

7) If the T carrier is set to AMI, verify that the CO (Central Office) has inverted the D-channel

8)Attempt to reset the PRI by disconnecting the cable at the 100D, wait 1 minute and then reconnect the cable

9) Run the CSU Loop back test to a 103 loop back or loop back plug towards the Magix at the Smart Jack

10) Verify that the Technician , while programming, did not program the PRI, then reprogram the T1 and then reprogram back to PRI. If so, system erase the Magix and re program the PRI and retest.

11) Cycle Power on the Magix

12) Verify the configuration of the CO (Central Office ) switch with the CO Technician
A)    If the CO is a 5ESS make sure they are running ATT Custom
B)    If the CO is a DMS 100 and/or DMS 250 make sure they have
Variant= NTNAPRI, (L1 flags in Trunk Sub Group = Yes) If set to ‘NO’ the D channel will act problematic
C)    If DSX600E make sure Profile =p250.

13) Have the CO restart the PRI and determine why the D channel didn’t come up.

14) Verify the continuity for the T by having the CO run a stress test to a loop back at the CSU

15) Replace the 100d

16) Replace the Processor   

17) At  this point the problem has to be a Network issue.

MORE PRI TROUBLESHOOTING TIPS:

Cannot dial international long distance calls.

* on some PRI facilities, it is necessary, in the Special Service Table, to change
the “Type Of Number” entry for international format, from ‘international’ to ‘national’

Can Call local, but are unable to dial any long distance numbers

·    Check the “Digits to Delete” section of the Special Service table. If there are digits being deleted, change all values to 0.  These digits send the dialing prefix ( 011, 01,1, etc) so the T1 carrier knows how to process the call, and are needed by some (mostly local) providers.  If the T1 is maintained by a long distance company like AT&T or Sprint, the prefix is not generally used so they are deleted.


Can dial local and long distance toll calls, but are unable to call toll-free (800, 888 etc) and / or intra-lata long distance.

*It may be necessary , under some circumstances, when all of the other Special Service Table entries are set at default (3 3 2 2 1 0 0 0), to change entry 5 to a 1.  Why this works is not documented, but has cleared trouble on several occasions.

Everything in programming looks  good , but still can’t call in or out. Provider may report
That they cannot see the ‘D’ channel.

*Verify with the vendor that the “Switch Type” is correct, and that the appropriate protocol is being used. The protocol for the DMS-100 and other Nortel switches is NTNAPRI.  The protocol for 5ESS and other AT&T switches is AT&T Custom. Also for DMS 100 switches the L1 flag in the ‘Trunk Sub-group’ table is to be set for ‘Yes’.

After a reset of the 100DS1 card a cold start of the switch or a brief disconnection of cabling for loop back testing, the T1 appears to come back up but calls cannot be made in or out.

*When a PRI connection is lost (for whatever reason) the T1 will normally reset itself and rebuild the connection to the Magix.  To do this, the “D” channel is established first and then the “B” channels are brought up either one at a time , or globally(all at once).  This is particularly significant because the success of the restart is entirely switch dependent.  If the Switch is a DMS-100, DMS-250, or DEX600E, it expects Nortel protocol.  Whenever the switch is reset, this protocol specifies that the first Layer-3 “D” channel message must be a global RESTART message (bringing the “B” channels up all together) sent from the network switch to the Magix.  If the switch is a 4ESS or 5ESS, it expects AT&T protocol. Whenever the switch is reset, the first Layer-3 “D” channel message sent from the Network switch to the Magix must be a “ B” channel SERVICE message (bringing the ‘B” channels up one at a time)

This is a newly provisioned service and  unable to call in or out.

*Print PRI information. IF the customer confirms that the PRI service is relatively generic and id utilizing Direct Inward Dial, here a some things to take a look at.

1)Is the switch type entered and correct?

2)Is the number of “B” channels entered the same as the number of lines?

3)Is there any number entered in the TestTelNum Field? If so delete it.

4)Are they using Direct Inward Dialing? If so, make sure Incoming Routing is set to By Dial Plan.

5)Look at entry ‘0’ in the Call-by-call Service Table. Are the Patterns 0-9 entered?

6)Is the NtwkSer under Entry ‘0’, for the call by call service table, set to no service?

7)Is the NtwkSer under Entry ‘0’ , for Dial Plan Routing Table, set to “Any Service”?