atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's Smart Jack or not to Smart Jack?

When I refer to a smart jack, I am thinking of the "electrical interface" type of smart jack. Are they known by something else? The telco can send a loop up/down command to the termination point and test the line out.

Ok...why would the telco terminate on a 66 block over one of the devices I describe above?

The answers will lead me onto more questions but I'll use this as a starting point.

Regards,

Rick

The smart jack is typically a box on the wall with some lights and at least one circuit board visible behind a clear plastic cover, has at least one RJ45 jack, and a cable going to either the RJ21x block or other demarc. The smart jack converts the incoming 2 pair line to an RJ45 T1 or PRI line, you need a CSU/DSU between it and your equipment to handle the protocol translation. The smart jack and the cable going to it are the phone company's property and their responsibility to fix.

In a word lazy.

Many times here they will leave circuits on the outside of the building.

Often the SMARTJACKS for an office building are in the Main phone room/closet where all of the phone lines come in, and there is a "shelf" with many circuits (smartjacks)in it.
The individual smartjacks are extended to the particular office suite via the 25 pair feed cables to the 66 block in the office. Generally they are then hooked up to a special RJ48X jacks with shorting bars in them.

~Don~

A smart jack is nothing more than a jack with shorting bars that put a loop on the circuit when the modular cord is unplugged. The unit you are taking about, where telco sends out a 2713hz freq. to loop up to test the circuit is ahead of the smart jack. Some loop back devices do have a "smart jack" internally wired to keep the circuit "alive" if it's unplugged.

Sorry to complete your question if they bypass the loop back deivice the circuit couldn't be balances as all the gain and slope settings are in that loop back unit. Old ones were simply called 829's
Bill

[This message has been edited by justbill (edited January 31, 2005).]

Thanks for the answers. So in a perfect world, the telco would terminate on an 829 at the telco entry point for the facilty then extend the circuit to the modular jack w/shorting bars. Right? I've always refered to the 829's as Smart Jacks...incorrectly I guess.

Next Question:

When the telco terminates a T-1 in a facility, it has to have a certain amount of signal strenght, right? And is this signal strength measured in gain? And if the signal strength is a bit on the low side, can they increase the gain or adjust the LBO for that T-1? If so, where would they do the adjustment...at the 829?

Again...thanks in advance for your help!!

Smart jack is another abused term, It kind of' depends on who you talk with and you will get some different answers. The NIU (Network Interface Unit) is most often called the smart jack. The NIU is usually the Telco’s d-marc unless extended by them, usually on a 48x jack (shorting pins) or 48c jack (no shorting pins). The 48x is sometimes called a smart jack because of the shorting pins. The NIU is remote loopable from the C.O. There are many varieties of NIU's but all pretty much do the same thing. They provide demarcation; a testing point, protection, line status and some log a trouble history. T1 NIU's are looped with digital codes. The 2713Hz is for looping dedicated analog ckts. like 9.6 ckts. Etc....

WOW you guys got it made. If I get label I think its a good day. Jacks and everything huh?

SST is correct, was having a senior moment. The Network interface unit it where telco hands off a T-1, unless the sub pays for an extended DEMARC. Sorry about taking you down the wrong path. As SST stated the 829 type loop back units are for private line data type services. Your other question on levels is yes there are level requirements, but depends on how you get the T-1 as to what they are...and again this is a senior memory taking to ya. Fiber is 0 db and if I remember right copper is -8 db.

T1 Smart Jacks, AKA: T1 NIU's, depending on the LEC, perform more than just loopback continuity functions. The lates generation of T1-NIU's also contain Performance Monitoring, or PM, data. PM data is monitored in both direction of the T1 signal path. Typical PM data collected would be BPV, Loss Of Signal, excessive zero's (Line events), and Path Errors, such as CRC-6 for ESF, frame bit errors for SF frammed circuits. Timing slips are not typically tracked by NIU's. One other usefull function by most current Ti-NIU's is that it hasthe ability to notify the network (Telco CO) that the CPE has either been disconnected, of has failed at the input. When a T1 circuit losses framing into the NIU, and where the signal has degraded to the point where upstream MUX equipment invokes an unframed all ones (AIS), the T1-NIU will send a modified AIS known as AIS-CI. AIS-CI, and RAI-CI, CPE fault yellow alarm, have been in the ANSI standards since the late 90's. Typical CPE eight pin jack interfaces are configured as RJ48C. The 48X interface has been phased out by "most" Telco's since it would defeat the AIS-CI feature should the CPE disconnect from the network interface. One additional note. HDSL remote units have incorporated the very same, if not similar operational functions of T1-NIU's, to include in-band loop up/down support for FT1 circuits (Verizon Territory) using the DDS NEI/RPTR loop codes.