[asterisk-users] Slightly OT:CSU on Digium cards, and it's requirement

[Jeff Davis]

C F wrote:
> No, I installed the system, it goes from smart jack to the PRI card in
> the Panasonic KX-TDA200 thru the 0290 card
> 
>> When I first started working with T1's, most CSU's were external.  I still
>> have several of them in storage in fact... and I still use external
>> CSU/DSU's on my production network today. :-)  I'm typing this message and
>> it will be sent over a T1 connected to 2 external CSU's before it reaches
>> the internet.
>>
>> Bottom line is, no matter what the FCC says... and if somehow you managed
>> to get it to work without a CSU... I believe the phone company would have
>> a fit if they knew you connected equipment to their network without a CSU
>> on it.  They're very big on standards-compliance and stuff like that.
>> Sometime look into their rules and regs about colocating equipment inside
>> one of their CO's...  it's very very strict.
> 
> The last thing you say is why I am asking this question. The
> compliance doesn't realy bother me that much, what I am afraid is if
> the provider notices this and decides to cut it because of that.

Several points:

Your card does not contain a CSU, but you probably already know that. I 
just mention that so that everyone can stop scratching their collective 
heads. There was an FCC requirement for the functions of a CSU, but I 
don't know if it's still in effect or if it matters for you. (see below)

The CSU is as much for your protection as the telco's. The CSU helps to 
isolate you from things like lightning strikes, and electrical hazards.

Most, if not all, of the functions of the CSU are handled by the smart 
jack these days. Line conditioning being the exception. Most smart jacks 
provide loopback, diagnostics, and in some cases line monitoring.

You may not get any help from your provider if you don't have a CSU on 
the line, but you will probably not be cut off since the smart jack is 
providing the functions required. This is a very different situation 
from the past when diagnostic and loopback functions were only available 
through a CSU.

I mentioned line conditioning above. Keep in mind that your service is 
working now, but if conditions should change, and the signal degrades, 
you may experience an outage. It's my understanding that a CSU will help 
prevent that.

So, no, you don't absolutely HAVE to have a CSU these day if the 
conditions are just right, but it's cheap insurance against some types 
of damage and signal loss, and will increase the likely-hood that your 
carrier will actually help you if there's a problem.

--
Jeff Davis
Netsource Consulting