atcomsystems.ca/forum Forums TDM Business Telephone Systems Toshiba Telephones & Systems Toshib 424 with new PRI..

Do we need to have a CSU for this application, we are about to install a new PRI on a 424 do we need to have a CSU/DSU if so why and if not what problems will occur, just need some clarification.

Toshiba requires that you have one. There's been a lot of discussion about this: https://www.sundance-communications.com/cgi-bin/ultimatebb.cgi?/ubb/get_topic/f/22/t/001527.html

no you dont

This would be why you have 1 star and the moderator has 5. By FCC rule you are required to have a CSU. And it is a good way to keep the finger pointing down to none. Sure your PRI/T1 may come up and run without one but it will cut down on line loss and framing errors. And if you have issues and call Tech support do you know what the first thing they will ask you? Do you have a CSU? no Well get one and call us back.

From a FCC search

FCC registration of CPE is required, I agree. However the technical merits and realities do not always agree. FCC Part 47CFR68-97, and the newer interim TIA/EIA//IS-698 (Pending industry replacement of FCC part 68) does not spell out the requirement of a CSU on a DS1 line termination (PDF versions available upon request). However, it is to the customers advantage to have a T1 CSU in-line with the T1 circuit to insure that the incoming signal level is within range of the CPE DS1 LIU. The premise equipment, by virtue of FCC compliance, is require to meet minimum standards relative to DS1 pulse shape, 1's density, timing variation relative to 1544000Hz, and DS1 signal output power to the NI.

ANSI T1.403 provides those necessary technical parameters that customer and LEC equipment must jointly meet at the network interface. However there is nothing in print that states that a T1 CSU is required. However, I am under the opiion that a CSU, or at least a DS1 regen, is required to meet DSX level regquirement of most CPE T1 LIU equipment components.

CSU's don't have to be costly but they are an intelligent trouble shooting tool. There are first, second and third generation Adtrans that go from less than a c note up.

The Adtrans have two jacks, Network and CPE. If you unplug either RJ45 cable, a light will come on indicating the fault.

I had a customer with eMpower and twice I had to run out there to tell them eMpower was down again. Then I put a note on the wall with an arrow to the "Net Loss" light and said that if this comes on, call eMpower, not Bunnie as your network connection is dead again." No more wasted calls.

Regardless of FCC regulations or personal opinions you absolutely positively need a CSU if you install a PRI on a DK424 or DKi series system when using a RPTU card. Nine times out of ten the circuit levels are too low causing network slip errors. The CSU not only gives you a testing point past the NIU but it also conditions the circuit to make share it's at the proper levels before your equipment it attached. If you use a BPTU card it has a conditioning circuit built in to provent level issues. Like mentioned before a CSU is also a testing point past the NIU and should be installed. IF YOUR NIU IS BAD YOUR SWITCH ISN'T GOING TO SCREAM IT OUT !

Thanks Computrak