atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's Media Converters

Lightninghorse,

Thanks for the reply. Yes, they are 021 modules and I have switched every setting so many times I fear the switches may go bad. We are using Adtran ACE CSUs and they, also, have switches. Same deal. The very first thing we tried was to move the CSUs to a mid point, more or less, to see if anything would happen. That did improve the situation, somewhat, and that is what lead me to install the fiber and put the whole distance thing to bed. Moving the CSUs also caused some other minor problems (slip and ber errors started to climb and, every now and then either T1 would lose sync) and moving them back resolved those problems.

When the circuits were first installed over ten years ago, we made sure the xmit and recv T&R were in separate binders and even went so far as to install another 25 pair PE-39 alpeth to further isolate the T1s. That worked well, for over ten years through two carrier transplants. However, Paetec is insisting the hop is too long and that is another reason we installed the fiber.

Rcaman

Here, as promised, is the result of this ardious journey.

The MUX units were installed on Tuesday. Right out of the box and connected, they worked perfectly. All I had to do was adjust the CSUs back to 133' (minimum) and cancel out the yellow alarms. It was the slickest and easiest equipment installation I have ever done in 45 years of telephony.

I was working at the PBX end and another one of our techs was at the smart jack end. We had a phone connection going so we could report back to each other the condition of the smart jack, the MUX and the PBX. While connecting the MUX at the smart jack end, my tech said "The smart jack LEDs indicate AMI SF. The MUX fiber link LED is green and the T1-E1 ports are green. Good to go." With the exception of the smart jack, I had exactly the same indications. I told him I was going to place a call to him on his cell phone. I did and he answered and said "did you do something in the switch? The smart jack LEDs indicate B8ZS." I said, no, but when I checked the channel status, it said B8ZS. I checked the T1 forms and the T1 condition was programmed AMI.

So, I waited two days and called the customer and asked how things were? She said "The delay in answering is gone. The volume levels are great, both ways. But, we are still getting random cut offs and wrong numbers dialed." I said uh-huh.

So, she asks me to talk to the person at Paetec that's supposed to know all the answers. As usual, she was arrogant and insisted we needed to change out the CSUs because that's what her testing has determined was the problem. Now, she maintains, distance was NOT an issue! I mentioned the smart jack indications and she said, that doesn't mean anything!

So, just to prove a point, I installed two brand new CSUs AND replaced both T1 modules in the PBX. SAME PROBLEM! Huh....really? The customer knew I replaced the equipment but Paetec didn't. When I called Paetec and asked about the condition of the circuits, she blythely stated: "Until you change out the CSUs, we aren't going to do anything more. All our tests are conclusive that it's your CSUs that are at fault." I asked her when she did her latest test? She said "This morning." (Friday). It took all I had not to scream LIAR in the phone. All I said was "I doubt your testing showed anything but a lot of errors and you really don't know where the errors are coming from." Then I said "Please tell your circuit engineer to check over his/her work and make sure it wasn't engineered as B8ZS instead of AMI. If it was engineered as AMI, then you need to have a chat with Verizon."

So, my fine feathered friends, let my misery be for your profit. NEVER trust the carrier and don't ever let them know you know more than they do. I know, you are all thinking, did the LEDs on the smart card show AMI or B8ZS BEFORE the fiber was installed? Yes, they did indicate B8ZS on the smart jack and in the link status on the Mitel. But, Paetec's "brain trust" said that was because the line length was too long and that's a "perfect indication" of line loss. Really? Huh!

By the way, the Transition MUXs are fantastic and work beautifully. They come as 4 T1-E1 x 1 serial port or 4 T1-E1 x 1 ethernet port all over one pair of either single mode or multi-mode fiber with your choice of ST, SC and LC connections. The data rate between MUXs is 155 Mb/s, plenty wide enough for 4 Ts and a 100 Mb/s ethernet.

Rcaman