How to – T1 Circuits and Wiring

      30 Comments on How to – T1 Circuits and Wiring

I’m not sure how many circuit turn ups I have been a part of that just fell through because the on site technician couldn’t get a CD light on the WIC card.  Moreover, I think the number of turn ups that I have been a part of that went completely as planned are fewer than 5%.  The reason?  Wiring.  Almost 99% of the time if there is an issue with a T1, its because of the wiring.  I’m going to start by explaining some of the basics of T1 wiring, discuss some relevant terminology, and pepper in some of my own experience throughout that might help your troubleshooting.

2 wire or 4 wire?
I can’t tell you how many people I have heard complaining about having a ‘2 wire’ T1.  They wonder why they would pay T1 prices for what they equate to a ADSL circuit.  They have a point; if it’s 2 wire, it certainly sounds like a DSL circuit.   The fact of the matter is that both 2 wire (single pair) and 4 wire (dual pair) T1s do exist.    The interesting part of this discussion is that regardless of whether it’s a single or dual pair circuit you’ll ALWAYS have dual pair coming out of demarc and going into your WIC card.  T1 circuits traditionally use 2 pair.  However, with the emergence of better standards and technologies the telco is now, in most cases, able to deliver the T1 to demarc over a single pair.  How do they do this?  In most cases they use a version of HDSL.  HDSL stands for high bit rate digital subscriber line.  Now, you might be wondering why the telco is selling you a DSL circuit and magically converting it into a T1 at demarc.  The concept is, for the most part, fairly simple but it took me a very long time to fully grasp the entire picture.  The basics of it is that the only single pair part of the connection is between HTU’s.  HTU stands for host terminal unit and there is usually a HTUC (HTU Central Office) and a HTUR (HTU Remote Location).  The span of copper between HTUs when using HDSL is single pair.  Without going into too much detail, the HTUs do the conversion for us back to dual pair standard T1.  Worried about some of the normal downsides of DSL like overloading or over-subscription?  No worries, HDSL is just like T1s.  They are either in sync (full 1.544 up and down) or out of sync (not working).  Next time you have a T1 installed, ask the telco tech if you can watch him do his cross connects.  He’ll probably install a T1 card in an available cabinet and then run a single pair of wire off ‘his’ (the telco’s) blocks into the cabinet.  Then coming off of the T1 cabinet he’ll run dual pair over to, what is in most cases, a 66 block where he’ll loop and tag (more to come on what that means below).  The point that I want you to get out of this section is that T1’s can be delivered 2 wire or 4 wire but any wiring you’ll be involved in (unless you are the telco) is going to be standard 4 wire T1 cabling.

Terminology
Now that I have thoroughly confused you, let’s go over some of the terminology for wiring and T1’s
Demarc (Demarcation Point) – Think of it as the end of the telco’s responsibility.  That’s where they terminate the circuit and hand it off to you.  If you have issues with the circuit the only thing they can do is test from demarc back towards them.  The rest of the wiring (between demarc and your WIC) is your problem.

CO (Central Office) – This is where all of the telco’s equipment is located.  The circuits that are terminated at your end in your buildings demarc are terminated at the telco’s end in the CO.  COs are sometimes also called ‘local exchanges’.  Think of it as a building where lots of connections occur.

TLM (The Last Mile) – Regardless of the fact that it isn’t usually a mile any more, the term refers to the connection between the CO and the client’s demarc.   Most of the time it’s significantly longer than a mile and with optics it can be much longer.  Sometimes it’s referred to as the first mile or local loop.

ILEC (Incumbent Local Exchange Carriers) and CLEC (Competitive Local Exchange Carriers) – I only bring up ILEC and CLEC because you’ll most likely hear about them somewhere along the line.  There’s a very LONG story here about AT&T being the only phone company in the US and during the 80’s and 90’s the government made AT&T basically become seven smaller companies.  These companies are called ILECs.  Basically, the big seven own the majority of the copper laid all over the US.  That being said, it’s hard for smaller ISP’s and circuit providers to get a hold in the market when they don’t have any of the lines.  Long story short is that the government forces ILECs to let CLECs rent equipment in their local exchanges so that they can provide services as well.  Hence, sometimes you buy a circuit from a smaller company but still need to deal with AT&T (the ILEC) during provisioning.  ILEC in most cases is the big company who owns the equipment and CLEC is in most cases more a less a smaller sort of reseller.

UTP (Unshielded Twisted Pair) – You should know this one but for the sake of being clear I’ll define it again.  Think standard Ethernet cable.  The only shield is the rubber wrapped around all 4 pairs in a standard Cat5 cable.

STP (Shielded Twisted Pair) – The real difference here is that there is either a cable or pair shield in the cable.  Some say that true STP is only the cable that has each pair shielded independently while others will say that STP just has to have a single shield around all of the cables.

ISTP (Independent Shielded Twisted Pair) – ISTP cable that has shielding around each pair.  Sometimes referred to as ‘T1 wire’.  I’ve see it sold in 2 and 4 wire configurations.  As mentioned in the STP definition, some people will call ISTP STP.  I make a point of saying ISTP when I’m referring to a cable that has each pair shielded separately.  I think in some cables you can still get grounding wires on each pairs shield as well.  If you do, only ground on side of the run.

HTUC (HDSL Terminal Unit Central Office) – As defined above, the equipment on the telco’s side of a T1 that does the HDSL magic.

HTUR (HDSL Terminal Unit Remote Location) – As define above, the equipment on your side of the T1.  Sometimes also referred to as a T1 card or Line card.  After the HTUR, you’ll have dual pair standard T1 wiring to work with.

Ring and Tip – If you actually understand the reference and are under the age of 30 I’ll buy you a beer.  Ring and tip comes from the old days where telephone connections were made at switchboards by plugging a  cord with larger head phone-like jacks between two callers to make the connection.  The ‘tip’ would be the wire that was on the tip of jack and the ‘ring’ would be the wire connected to the ring around the jack.  If I recall correctly, the ring was used to sync the call and actually sent the signal to make the other phone ring (funny huh?).  The tip connection was actually used for the phone call.  Ironically, these terms are still around today and every T1 cabling guy I have ever met still uses them.

Loopback – Much like the loopback on a network interface a circuit loopback crosses the receive and transmit wires to cause a physical loop.  You can make a loop back jack yourself (we’ll talk about that more below) for testing purposes or most WIC cards let you set loopback in software for testing.  Most T1 testers prefer the physical loop back over the software.

RJ48X (Smart Jack) – A T1 should be terminated in a RJ48 junction box.  Never heard of RJ48?  Thought I meant to type RJ45?  Wrong!  RJ stands for ‘registered jack’ and while some people think that there is a physical difference between RJ numbers there really isn’t.  Most of this confusion comes from the difference between RJ11 (having a 6 position connector) and RJ45 (having a 8 position connector).  So why does RJ48 use a different type of connector?  Because RJ more or less defines the type of wire used and their associated pinouts within the connector.  For instance, RJ45 specifies UTP and a send/receive pins of 1236.  RJ48 specifies STP and send/receive pins of 1245.  Sometimes RJ48 connectors have an extra side groove so they won’t fit in a standard RJ45 jack.  That being said, I still see tons of people who use RJ45 jacks and connectors to do T1s.  You just need to properly understand the wiring patterns to make it work.  Back to what I was initially talking about though, an RJ48x jack has what are called grounding (or shorting) bars in it.  When you plug a connector into the jack the bars move out of the way allowing the connection to flow through the wire.  When you remove the connector the bars come back into place which ground pin 1 to 4 and 2 to 5 causing a loopback.  Loopbacks are a big part of T1 testing so its a good thing to have a jack that has this characteristic.

CPE (Customer Premise Equipment) – Basically the router with the WIC that you are terminating the T1 in.

WIC (WAN Interface Card) – The card you terminate the T1 in.  Usually has a built in CSU/DSU

CD (Carrier Detect) – On a Cisco WIC card its the green light that comes on to tell you that the WIC has sync.  You need a CD light on the WIC before you proceed with turning up a circuit.

Extending the Dmarc
Now that we have some definitions lets talk about the actual wiring.  Since we are past the single and dual pair debate we can talk about straight T1 wiring which is ALWAYS dual pair.  In most cases when you order a T1 circuit a telco tech will come out to your building demarc and connect the circuit up to some point of demarcation.  That being said demarcation can mean a lot of different things.  Lots of demarc rooms have telco equipment on one side of the room and then a wall of blocks and biscuit jacks that have all of the circuits on them.  A typical T1 install involves installing the T1 card and patching the connection to it.  Then they’ll patch the circuit from the T1 card either to a 66 block or a RJ48x jack.  Most of the time in a large building you’ll see the circuit being terminated on 66 blocks where the tech will ‘loop and tag’.  Since there isn’t anything in line to automatically loop the circuit for testing the telco tech will usually put a pair of wire between the send and receive pairs on the 66 block to physically loop the circuit.  They’ll usually leave excess wire on the loop and tie the circuit ID tag onto the loop wire.  Then when you come into the picture you can pull off the loop wire and extended the circuit from the 66 block to house pairs going to your suite where you can terminate in a RJ48x jack.  Now is an appropriate time to talk about the actual wire used when extending the demarc.  If you don’t already have house pairs running to where you want to terminate the circuit and you aren’t low voltage certified call a wiring contractor.  There are all kinds of things to take into account when extending a circuit such as wire type, extension length, interference, binder groups, etc..  If you decide to do it yourself, I suggest ISTP (T1 wire) and if you can’t get that, run two Cat5 cables with one pair in each wire.  I’m not even going to touch on the subject of how long the extension can be.  I’ve heard any where from 10 to 100 feet with Cat5 alone.

T1 Pinouts and Wiring
It’s pretty straight forward
Pin – Description
1 – RX Ring
2 – RX Tip
4 – TX Ring
5 – TX Tip
Now what isn’t as straightforward, for some reason, is the big picture view of this.  For some reason the first thing that any on-site tech does when he doesn’t get a CD light on the WIC card during turn up is blame the wiring guy.  What you SHOULD do is verify the wiring into the jack and the cable you are using to connect the WIC to the jack.  95% of the time the wiring guy got it right, he just didn’t tell you how to finish the wiring.  The most common issue is cross over.  It seems to me that some cabling technicians assume you’ll be using a T1 cross over cable and others assume a straight through will be used.  If a straight through is going to be used, you can simply use a normal Cat5 patch cable as the pinouts on both sides of the wire will be identical.  If you need to cross over before you get to the WIC a standard Cat5 cross over cable wont work.  Why wont it work?  Because a T1 uses pins 1,2,4,5 and a Cat5 cable uses pins 1,2,3,6.  Below I show you what the connectors for each type of cross over would look like is using the full 4 pairs.  The concept here is that you simply need to cross receive and send pairs so that send on one end goes to receive on the other.

Cat5 Cross over Cable

End 1
Pin – Description
1 – Green White
2 – Green
3 – Orange White
4 – Blue
5 – Blue White
6 – Orange
7 – White Brown
8 – Brown

End 2
Pin – Description
1 – Orange White
2 – Orange
3 – Green White
4 – Blue
5 – Blue White
6 – Green
7 – Brown White
8 – Brown

T1 Cross over Cable

End 1
Pin – Description
1 – Green White
2 – Green
3 – Orange White
4 – Blue
5 – Blue White
6 – Orange
7 – White Brown
8 – Brown

End 2
Pin – Description
1 – Blue
2 – Blue White
3 – Orange White
4 – Green White
5 –Green
6 – Orange
7 – Brown White
8 – Brown

Do you see what the issue would be if we were using a standard Cat5 cross over cable?  Pins 1 and 2 cross correctly but 4 and 5 don’t cross at all in the Cat5 cross over.  Just keep this in mind when you are troubleshooting the wiring.  This what the end result of the T1 wiring has to be.

Telco TX Ring – CPE RX ring
Telco Rx ring – CPE TX ring
Telco TX tip – CPE RX tip
Telco RX tip – CPE TX tip

I seem to be throwing out a lot of percentages so I might as well stick with it.  I think about 60% of the time when I don’t get a CD light on a WIC card I can use the same cable and simply swap the pairs in the RJ48X jack.  If you don’t like messing with jacks you can simply carry both standard T1 patch cables as well as T1 cross over cables in your bag.  One of them ought to make the connection work.

T1 Loop Back Jacks
Another area of disagreement between cabling professionals is what pairs need to be looped to cause a loopback.  The loop back jack I carry in my bag loops pin 1 to pin 4 and pin 2 to pin 5.   That sort of configuration loops both pairs.  Others have told me that you only need to loop pins 1 and 4 since those are the only ones used for syncing the connection.  I think I’ll stick with looping both pairs to be safe.  You can use any old RJ45 jack and some cross connect to make the loop back jack.

Conclusion
I hope this was more helpful than confusing.  I tried not to go into so much detail about the telco side of things as most of you will only be concerned with the T1 after demarcation.  And I realize that I didn’t get into as much detail about some items.  Unfortunately there are entire books written about T1s so a blog entry can really only graze the surface.  If you read this and disagree with anything I’ve said, I’d love to hear from you.  All of this is based purely on my experiences with T1 circuits.  Any additional input would be appreciated!

30 thoughts on “How to – T1 Circuits and Wiring

  1. Raul

    Question?

    Our circuit comes into a 66 block. From there, it is connected by a single pair. Connections look very simple at both ends. Can we move the circuit about 250′ from the 66 block using 22 AWG solid Cat5e (100 Ohm T1/DS1 cable)with conductors being arranged in individually shielded pairs? We will be place this wire inside conduit that already has two other Cat5e cables (UTP).

    Thanks

    Reply
    1. admin

      Hi Raul – Thanks for the question. Thats a tough one. We’d need more info for instance, Im assuming you are talking about a single pair prior to your T1 card. If thats the case then we are talking about moving the Demarc? Let me know if Im wrong but that sounds like what you are talking about. If thats the case the only advice I can give you is to contact the ISP that owns the copper. They really need to be the ones moving it. If its after Demarc then you should get a certified low-voltage technician in to make sure that your proposed run wont cause any issues.

      Sorry for the delay in response, its been busy!

      Thanks for reading – jon

      Reply
  2. Chuck

    Jon thank you for your article How to – T1 Circuits and Wiring, I am currently preparing to extend T1 connections from the Demarc to equipment at several locations. Paperwork that I have received from a third party that will be part of my MPLS network reads “ Demarc (RJ48S) to be located in TELCO Room” which refers to a Verizon tech bringing in the T1 to the building. With the reference to RJ48S I’m wondering if I’m to use pins 1 & 2 and 7 & 8 and if this is correct can I use an RJ48X wall jack on the side of my equipment? Thanks Any help would be appreciated Chuck

    Reply
    1. admin

      Hi Chuck! Let me make sure I understand what you are asking first.
      So the telco is bringing a T1 into demarc which you plan to extend into a wiring closet and terminate in an additional jack so you can connect your router directly to your jack on the wall. Is that correct?

      If so, I have to admit that I dont have much experience with RJ48S jacks. In fact, I have only heard of them. Around here, everything is RJ48X for T1. I think they sometimes use RJ48S’s for DS0’s or smaller circuits. It might be easier for you to just be there when the guy is bringing the circuit in and have him put a RJ48x in or ask him how to wire it up to your closet. What does the connection from the demarc to wiring closet look like? House pairs on 66 blocks? Most of the extensions I have done were on 66 blocks already, looped and tagged from the LEC. Then I just pull the loop and run pairs over to my 66 block. Then I put a RJ48x up in my switch closet and connect the jack to the 66’s again.

      It sounds to me like your provider is terminating the circuit in a RJ for you. If that’s the case, I would imagine if they put in a ‘S’ type jack you could just wire it per the wire mapping as you described. However when you are unsure about wiring, test this one step at a time. I might even take the router with me and plug it in at demarc, off the 66’s, and then in the wiring closet making sure I had CD each step of the way.

      Does that make sense? Let me know if Im way off base.

      Best of luck!

      Reply
  3. Len Goldberg

    I have a question about the tip and ring color pattern of T1 cable and if continuity Iowa relevant, which I assume it is.

    Tip (Positive) Ring (Negative)
    (Standard colors) (Standard colors)

    White/blue. Blue/white
    White/Orange. Orange/white
    White/green. Green/white
    White/brown. Brown/white

    But your color chart for T1 two pair shows the tip and ring (which to my mind indicates a specific polarity of positive or negative), as follows.

    Tip (Positive) Ring (Negative)
    Pin outs. Pin outs

    1. W/green for TX Ring, but should be Green/White. . Should be White/green

    The rest seems O.K.

    Am I in error?

    Len Goldberg

    Reply
    1. admin

      Hi Len,
      Im not entirely sure what you are asking. Inverting the color combos doesnt make sense to me. Are you trying to say that ‘white/blue’ and ‘blue/white’ are different?
      Maybe I just havent had enough coffee yet 🙂
      Can you try wording the question differently?
      Thanks – Jon

      Reply
      1. John H

        Hi Jon,

        A few years after the fact, but I wanted to point out that the cable pairs are (or should be) two colors on each strand in the pair. For example, the first pair should be White/Blue and Blue/White. The difference is which color is more prevalent – White/Blue looks solid white with a thin blue stripe, while Blue/White looks solid blue with a thin white stripe. There are actually 25 different color pairs, and for cables with more than 25 pairs each bundle of 25 will have a color-coded band around them (using the same color scheme as the pairs themselves).

        So, yes: White/Blue is different than Blue/White.

        Cheers

        Reply
  4. Jim Berken

    I am extending a demarc for a T1 from an interface box installed by AT&T to a RJ48X jack in the equipment room. The terminals on the interface box are labeled: CT1, CR1, CT and CR. In the interface box there is an RJ45 jack with a short pigtail plugged into it. The other end of the pigtail goes to the terminals (screws) where I connect my wires. The jack pins 1 and 2 go to screws CT1 and CR1. Jack pins 4 and 5 go to CT and CR. Most documents I have read for how to wire a RJ48C or RJ48x say connect R1 & T1 to pins 4 & 5 and connect R & T to pins 1 & 2. This means the pinout on my RJ48 jack is not the same as the jack in the demarc box. Which is correct? Is CT the same as T and so on? All documents indicate T and R are transmit to the network and T1 and R1 are receive from the network but some documents put T & R on pins 4 & 5 and other documents put T & R on pins 1 & 2. Which is correct?

    Reply
    1. admin

      Hi Jim,

      The CT and CR naming convenstion never made much sense to me. I prefer good old T and R. Im assuming that its just ‘Circuit Recieve’ etc, but to tell you the truth I dont know that for sure. That being said, the polarity really doesnt matter. However, the correct way to do this would be to wire your jack as follows…

      CT1 –> Orange (pin2) T
      CR1 –> Orange/White (pin1) R
      CT –> Blue (pin4) R1
      CR –> Blue/White (pin5) T1

      Does that make sense? Is that what you were asking?

      Thanks – Jon

      Reply
  5. Craig

    So polarity match up does not matter on RX+ RX- and TX+ TX- ? pins 1,2 could be swapped between themselves and the same for 4,5 without causing any issues coorect?

    Reply
    1. Jon Langemak

      If I understnad your question, then the answer is no. They need to match up, just like any other standard cable.
      Telco TX Ring – CPE RX ring
      Telco Rx ring – CPE TX ring
      Telco TX tip – CPE RX tip
      Telco RX tip – CPE TX tip

      Reply
  6. Phillip

    Hi,

    Does the nomenclature “DCE” and “DTE” apply to T1? I suppose I’m asking: does signal always leave a T1 RJ48 on 4&5 and is signal always expected on 1&2? This came up in a recent conversation and I’m trying to figure it out. I do know that you have to be careful when talking to the telco tech because they will often put “TX” and “RX” in your terms, i.e. the pair they identify as “TX” on the block might easily be where you should connect your TX. So in a sense you might say the telco is DCE and your gear is DTE, but is this just a matter of naming or does an RJ48 ever send signal out on pins 1&2?

    Thanks much

    Reply
    1. Jon Langemak

      It all depends on where the circuit is terminated. If its one the actual PE equipment the cabling usually makes sense. If its extended (100 feet or 1 foot) then all bets are off in most cases. Most cablers Ive seen dont care as long as they keep the pairs together. Or is that now what you are asking? 😉

      Reply
  7. RJ Pfeifer

    You owe me a beer. 🙂 I am 21 and know what ring and tip is. In the audio world it knows as a TRS (Tip, Ring, Sleeve) jack. The tip can be used for one connection, while the ring can be used for a second. In audio, it is generally used as an insert cable on boards where the tip sends a signal from the board to a TS jack into a compressor or eq, and A second TS jack which is connected to the ring on the TRS returns the signal back to the board after it has been processed.

    Cheers,

    RJ

    Reply
    1. Jon Langemak Post author

      Ha! Well done! I had forgotten that I used to write posts where I offered my readers free drinks 🙂

      Reply
  8. Mark

    Hi Jon,

    Great info, thanks for posting. I have a situation that appears to be fairly common and was hoping you could point me in the right direction. We connect two sites via two point-to-point T1 circuits. These circuits are combined into a Multilink 3mb circuit for data and voip traffic. One circuit has been generating input, crc, frame and overrun errors on one of the Cisco T1 WIC cards. The other three cards are fine. I have had multiple discussions with the Telco vendor trying to get confirmation that the circuit is good. I have swapped the circuit endpoints between the different T1 WIC cards on our Cisco router and saw that the errors followed the circuit to the other card. I am expecting to have the vendor come back and say that it is our wiring to blame even though I had our cabling contractor verify that our cabling was good. Any suggestions on where to look next to troubleshoot?

    Reply
    1. Jon Langemak Post author

      Hi Mark,

      From my point of view, you’ve done everything you can. You verified that the issues follow the circuit so it’s certainly not a problem with your gear. Is the vendor a telco? If so, if you complain enough they should be able to go into the demarc and do local testing with a T-Bird or something of that nature. If they see issues there, you are off the hook. If they don’t, have them run up to your router and test from there to see if the house pairs are the problem.

      Good luck!

      Thanks – Jon

      Reply
  9. Edwin M

    Hello Jon,

    I have a question. First off, im a newbie and in trying to save the company $ so I will try to do this connection,havent done this in a few years. If i don’t get it right then they will call someone one out. Not a time sensitive matter at this point. We have a T1 line that’s been dropped into the equipment room. Cross-connect one (1) T1 Circuit from Carrier Demarc to a Interface on RJ45 Jack at the phone board at the Service Demarc. Then from the RJ45 I will ge going to an IDF and from there to a MDF to our office. So from what I recall I have to punch down the T1 to the available block and from there to the RJ45 jack and from there fish my lines to the IDF to the MDF to our office? Would i be correct in my assumption or could you shed further light? I appreciate your time.

    Edwin

    Reply
    1. Jon Langemak Post author

      Hi Edwin,

      Can you clarify your question? Are you concerned about the correct pairs or are you talking about using CAT5 for crossconnect?

      Thanks – Jon

      Reply
  10. Pingback: T1 Circuit Pinout | MPLS

  11. Wayne

    Hi Jon,
    We were wondering if distance is an issue on 2 pair T-1 circuits.
    We are trying to send the circuit 600 to 1000 ft over copper, is this possible?

    Reply
    1. Jon Langemak Post author

      If I recall (it’s been awhile now) the max extension off a smart jack was 600 feet. Now that was the word I got from the carrier so that could be dependent on the gear they are peeling the circuit off as well. 1000 feet sounds way to long though.

      Reply
  12. G Comm

    Jon, we have a 25 pair outdoor D-marc.
    Nothing off it as of now. Current phone is Comcast.
    We have 2 T1 Ckts. coming in from AT&T. Can I run a 25 pair from the Telco / IT room to a
    66 bock on the inside wall opposite the D-marc and have the smart jack installed there, come off it over the 25 pair
    or should I request the smart jack be installed in the telco/IT room?
    The distance on the 25 pair would only be about 250 Ft. Max.

    Reply
  13. Rajish Cheruparambil

    I have a question. I have the T1 line provider provide a RJ48C jack. My router that I have purchased is a regular router/firewall with standard RJ45 jack. How do I connect between the two or should I strictly use a T1 capable router?

    Thanks

    Reply
  14. Charlie H

    Hi Team,

    I never received a straight answer from the ISP regarding the type of hand-off provided.
    What I did find out is our Juniper Firewall SRX100 Firewall would not communicate with this one customer location
    in Tucson Arizona. Through investigating it was mentioned you maybe handed a T1 circuit for example what we would use if installing a Router with a MPLS circuit and a CSU/DSU device .
    In this case I needed to order a more expensive model SRX210 with another RJ45 port module ordered seperate identified as :
    1-Port T1/E1 Mini-PIM for SRX
    and than add some code in the firewall to support a T1.
    My next question is how do i know if when i order a new circuit requesting a ethernet handoff.. Thats is what the ISP is actually providing before the install, and prior to me ordering the correct model firewall
    Of course now we have changed our model to a Palo Alto 500 or 200
    and here we go again with finding if a palo offers a slot for a T1.. if I need to go down that road again.
    Hope I spare you all the pain and thanks for the comments in this article

    Reply
  15. mariom martinez

    Hello,

    I would wondering if there is a reference that tells you what circuit goes to what pairs.

    Example

    DSL- 66 block ring –Pair 3 Rj11
    Tip —Pair 4 RJ11
    T1- 66 block ETC.

    Somewhere close to this format, but for all circuits. DSL, ADSL, t1, MPLS, pri.

    It would be most beneficial, thanks.

    Reply
  16. Ill

    Two wire HDSL, as stated above, delivers a four wire independent path bi-directional channel at 1.54400MB/s. HDSL is used by ILEC’s to deliver DS1 services to customer locations that are not served by optical carrier equipment, or wire extended from a a central ILEC hub, such as a controlled environmental vault (CEV) that serves a commercial campus environment.

    The best part of HDSL, and almost all versions, is the ability to catalog the health of both the DS1 circuit payload, and the HDSL envelope. Easily accessible from nine pin serial connector located at the remote HDSL, and CO unit, faceplate.

    Within the HDSL transport system are tools that will greatly help with identifying circuit level and HDSL faults. Most notably when ESF framing is employed, and where the customer has enabled “ANSI 403 Performance Monitoring (PM) terminal equipment. Once ANSI has been “Turned on” to a DS1, using the appropriate T1 test set, DS1 circuit performance information from both ends of the circuit can be observed from a single monitoring point.

    The ANSO 403 option can be identified in CSU equipment under various designations, such as:

    ANSI
    403
    PRM

    No to be confused by an older ESF PM standard: AT&T 54016.

    The ability to understand the difference between Near End and Far End, Line and Path greatly enhances the ability to identify the source direction of faults. ANSI T1-403, and T1-231 describes ANSI ESF Performance Monitoring (PM) function, and defines the individual parameters that affect error free circuit operation.

    s a final note, current vintage HDSL equipment since 2000 in the Verizon footprint incorporates ANSI 43 PM collection, and displays with FAR END/NEAR END statistics. HDSL user guides are helpful with understanding how PM is collected and displayed within each vendor’s product.

    Finally, my familiarization with HDSL equipment is tied to the many equipment RFP’s that were issued during my tenure at Verizon, and in specifying HDSL operation requirements that included PM collection, and display to assist the field technician win the troubleshooting process.

    ADC HRU 402

    https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahUKEwj_-5mXs9HRAhVIKiYKHdtjCGcQFggkMAI&url=http%3A%2F%2Fwww.te.com%2Fcommerce%2FDocumentDelivery%2FDDEController%3FAction%3Dsrchrtrv%26DocNm%3DLTPH-QI-1023-03%26DocType%3DSS%26DocLang%3DEnglish&usg=AFQjCNE8OPECj1LKc74YRJf0A7DxKV8r2w&bvm=bv.144224172,d.eWE

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  17. Tom

    Your information is very helpful. Thank you. Do you have more information on basic networking? I’m in the telecommunication industry, starting to connect IP phones and network phone systems togeather.

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