We are trying to bring up 2 T1, PRI, circuits between the MultiAccess unit and a Nortel SL-100, using National ISDN2. Our next step is to try Northern Telecom proprietary formatting and I have several questions about getting this working.

Can the unit be cabled directly into a T1 interface provided from a PSTN switch, in this case a Nortel SL-100 for ISDN. Or, do I have to insert some kind of CSU between the Multiaccess L1 interface and the SL-100?

The MultiAccess does not require an external CSU (external CSUs appear as T1 repeaters from our perspective). It can be directly connected to the T1 interface.

Is it valid to be able to loopback a T-1 into one of the Line interfaces of the box and go out of Red Alarm status (error code 64, which I'm assuming is following the T-1 spec for a Near-End LOS)?

You can insert a physical loop back cable into L1 of the MA30120 and it should come out of red alarm (looping pins, 5 to 1 and 4 to 2). The MultiAccess does not respond to Telco initiated loopbacks.

Traditional T-1 settings don't seem to appear with the T-1 PRI formatting, e.g. LBO, Clock Source. I'm assuming since we are plugging into a PSTN switch (SL-100) that the Multiaccess unit is expecting to receive clocking from the Network.

Yes, the MA30120 is expecting to derive timing from the T1 line. T1 Lines that come from the public switched network do not derive timing from the customer's premise equipment.


The RED alarm indication is coming from the management interface (Statistics/Logs - Line Interface Status). The LEDs on the front panel go to the LA (Link Active) when we plug the T-1 into either L1 or L2. We did discover the ESF with error correction is the only format that the SL-100 will link with. In fact, the SL-100 thinks the network is up and happy.

Here is the symptom we are seeing:

- On the Statistics/Logs screen, the indication is: Line 1:

RED Alarm
Framer Status: 64 0 0 0 0
Framing Error: 0 0
Code Violation: 0 0
CRC Error: 0 0
Errored Block: 0 0
Bit Error: 0 0
DL-Bit: 1 1 16

- When we dial the unit, the call is presented from the SL-100, and the Statistics/Logs - Modem Connections table displays the incoming call:

Port State Username
ttyMB11 Link Incoming

Then it changes to "Training" as State, but we are not receiving modem tone. I was trying to make sure we have the T-1 configured properly before proceeding on with the Modem troubleshooting part. It was concerning me that we had a "Red Alarm" on the Statistics screen.


When Telco thinks the network is up and happy and when our tty port goes from Allocated to incoming to training etc. then our T1 Line Interface is set correctly. At this point our Line Interface (under stats&logs) should reflect No Alarm.

I'm assuming You have not changed the "Modem Usage" from it's default of "RAS" (Modem Setup menu). The Usage should be RAS.

Go to the Administration menu and then select the System Tools menu. Then select Restart Server. It takes about 3 minutes for the unit to reboot and come back up.

What you have described (Telco is happy with the circuit, a call is routed to us, the state of the tty port changes but there is dead air
o answer) is consistent with the following:

New unit out of box: The first time upon entering the Line Interface setup page, the "line type" was at "E1 PRI". You then proceeded to change the line type to T1 PRI, switch type, etc.. You then selected the Save button, followed by the send button (this is all correct). When pressing the send button the MA30120 pops up and says the module will be restarted. What it doesn't say is that when switching between E1 and T1 the unit needs to be rebooted.