[cisco-voip] Clicking/popping noise on inbound side of PRI

[Vance Shipley]

Mike,

I would want to run a 24 BERT test from the CO to the Cisco.  Put the
Cisco into remote loopback mode and have Verizon run a BERT test through
that loopback.  This will test the Cisco LIU, the cable, the SmartJack
and everything else out to the CO.  You need to do this for 24 hours
'cause you don't have a 100% failure rate.  If you could reproduce the
eoors all the time you could draw conclusions earlier but as it is you'll
need to run long enough to know that you would have seen the problem.

If that test shows errors then you would want to restest with the loopback 
being provided by the SmartJack.  If it still shows errors Verizon will
accept responsibility and fix it.  If not Cisco will blame your cable or
take resonsibility.

Now as far as the cable goes, what is a "certified cable"?  Is it a
certified RJ-48C cable?  Or is it an ethernet cable?  I don't believe
a lack of sheilding is going to cause this problem however you need
to make sure you have your signals on twisted pairs.  RJ-48C uses pins
1&2 and pins 4&5.  You must have pins 1&2 use a twisted pair, and the
same for pins 4&5.  A flat "silver satin" cable will not work.  A cable
where the white-blue/blue-white, etc. pairs are not using the right pins
will not work.  A combination of two wires where one is <color> with 
white stripes and the other is white with <color> stripes makes up a 
twisted pair (e.g. white-orange/orange-white).

99% of the time these sort of problems are caused by cabling/connector
issues.

Next question:  where are you deriving timing from?  You must be 
clocking off the incoming T1 from Verizon.  If you are using an internal
clock, or clocking off another span which is not itself timed off
Verizon (or a higher Stratum level) you will have problems.

	-Vance