With my many years of experience I have run across a lot of technicians that have trouble in trying to troubleshoot a T1 circuit. This T1 circuit can be either a DTI or PRI circuit.Now you must be wondering what a photo of a backhoe has to do with a T1 circuit. You will see the symbolism of it as I explain.
A T1 circuit is a digital circuit consisting of 1.544 mb of data bandwidth. This bandwidth is divided up into 24 equal 56 or 64 kb channels depending on the framing format that you ordered. The most common types of framing and coding are ESF/B8ZS or D4/AMI. There can be other combinations but these are pretty much standards with ESF/B8ZS being the most common today. There are some wierd ones out there like ESF/AMI.
For more information on the acronyms click here.
Now for the meat of things. The starting point is the carrier portion of the T1 circuit. What I am talking about is the framing and coding portion of the circuit. These must match at both ends or it will never work, it must also match the T1 circuit that you ordered from the local telco.
Here is where the analogy comes in. Think of the framing and coding of the T1 circuit as the ditch and the individual channels as the conduits you are going to put into the ditch. You have to dig the ditch first.
There are 3 states to what I call the carrier portion of the T1 circuit (the ditch), Red Alarm, Yellow Alarm and No Alarm. The Red Alarm refers to the loss of the carrier. In other words your equipment is not seeing the T1 circuit at all. This can indicate a problem with the T1 circuit or your cabling on site. Yellow alarm indicates that the far end is having a problem. No Alarm is exactly what it means, your equipment can see the circuit and the framing/coding matches the T1 circuit and you are ready to move on to the channels.
Now that you are ready to turn up the channels (conduits), this is where it varies based on the equipment being installed. There are so many different posibilities that I can not cover them all here. Basically these channels must match at both ends also but it is not dependant on the T1 circuit. If you think of these as conduits, the ditch does not care what you put in them but the equipment at the other end does. You can not hook a phone cable to a high voltage transformer and expect it to work. So with that, you can not program one end as NI2 and the other end as Q.SIG and expect them to talk to each other. Just like putting someone that only speaks Swahili with someone that only speaks French and expecting them to be able to communicate with speach only.
That is basically all there is to troubleshooting a T1 but there are numerous ways to accomplish the same task so to each his own. But remember that you have to dig the ditch before you can put the conduits in the ground. To put this analogy into T1 terms, the carrier must be established with no alarm before you can bring the channels into service.
Sometimes it would be beneficial to call a professional to handle service and installation issues. You have to balance the cost of the service call against the cost of the downtime you will experience.
So now does the backhoe make sense?
