sundance-communications.com/forum Forums TDM Business Telephone Systems NEC Telephones & Systems Do I Need a CSU - Modern PBX...

We are a company that has traditionally prided ourselves on being thorough and doing things right. Historically, we have installed a CSU on every T1/PRI ckt that was connected to a PBX. We typically use the Adtran ACE.

On many sales deals, we find decisions are being based largely on price (we can save the merits of value and other arguments for later). By eliminating a CSU, I can subtract approx $500 from the total cost of a job, which in some deals makes us that much more competitive. We have a competitor that tells the prospect that they don't need a CSU on their equipment and the question invariably comes up on why we have one in our price quote if the other guys don't need one.

My question is this: Do I need a CSU on a modern NEC PBX (SV8100, UX5000, DSX, SL1100)? Aside from line conditioning and a diagnostic point, is it really needed?

Yes, unless you are coming off an IAD.

For a more complete reason why see the Adtran manual regarding Part 68 of the FCC regulations.

https://www.adtran.com/pub/Library/Manuals/Default/T1_ESF_CSU_ACE__4th_Gen__User_Manual.pdf

On that manual use find and look up FCC.

I think it might depend on how the circuit is delivered to the site. We have a number that come off of a fiber optic interface, and we never use a CSU on those. Or, if the smart jack is close to the phone equipment we don't use one either.

I'm sure we can say it's always recommended - but I have asked a number of the providers we work with, and most of them don't seem to care if we use the CSU or not.

My guess is we have 25% of our installs using a CSU, and 75% not....

My take would be to put it onto the user. Put it into your terms and conditions that the user specifically requested not to have a CSU.

So the SV8100 does not meet the FCC requirements under section 68? (I haven't bothered to look it up in their tombs of literature yet).

The issue of the CSU has been discussed here in the past. The gist is, it it required for loopback testing purpose past the NIU by the telco when you have a circuit delivered from the telco without an IAD, ie, if you are just plugging into the NIU, or, "smartjack". When an IAD is deployed, "IT" is the CSU as it is between the circuit & the CPE. Most PBX's these days have "built in" CSU's. I do remember the SV8100 does not although I think the PRT & DTI cards on the IPK platform did. I work for a CLEC now & if we deliver a facility based circuit, ie, direct PRI no internet, we do not install an IAD but we do install a CSU between the PBX & NIU regardless so we can loop up past the NIU when troublshooting remotely. Your competitor is not well versed in telephony, it would appear. Educate your customer & put it writing.