Monday, January 15, 2007

How Do You Turn A DS3 Circuit Into 28 T-1 Lines

Here's the story.....

You ordered a DS3 circuit to replace 20 T-1 lines you have. It is cheaper on the network side and everybody at the local long distance carrier said it will work exactly the same as T-1's. Now you're being told it will not (big surprise) and it is due to be installed in a few days.

The signaling you need is d4-AMI. The carrier wants to know if it will be either ss7 or PRI. Your equipment is too old for both.

How do you make this work?

You've heard about using a multiplexor or a mux. But how do you know if you are getting the right one and if it will work? Your equipment is based off of the D240sc t-1 rev1 dialogic boards. Plus you also use a 1980's phone system ( surprise for many businesses unfortunately). Ultimately, you need to have 28 T-1 lines from the DS3 circuit.

What equipment do you need? How should the carrier set up the DS3 circuit for you?

Okay here we go....

The first thing you need is to get the proper equipment.

Any M13 mux will break out the individual T1 lines from the DS3 circuit. The Adtran MX2800 should be okay but it will need the proper configuration. Unless you have a DC power plant you will want the AC power model. I would suggest you put it on an UPS also. Plus you'll want to get the M13 control card not the STS-1.

You will be using M13 framing on the DS3 circuit not C-bit. The DS3 bandwidth side of the circuit is referred to as the high-speed side. The T1 bandwidth side is referred to as the low-speed side. On the T1 side you will need to physically breakout the T1 lines.

For the MX2800 it appears you will need a couple of accessories. It looks like you will want to get the 64-pin amp cable to the RJ48 patch panel. Your T1 lines will appear on the patch panel in order, DSX-1 channels 1-28.

The T1 lines are individuals and need their framing and coding set for the type of T1 on a particular channel. For instance; channel 1 on the DS3 circuit is an SF/AMI T1 so you set the mux channel 1 for SF/AMI. Channel 2 is ESF/B8ZS so you set channel 2 for ESF/B8ZS, etc.

TL1 commands are pretty basic but can get complicated very quickly. Not all mux's use TL1 but it looks like the MX2800 does. The Manual with the mux should have the commands in it for you to follow for set up..

Basically it's fairly simple. You have a DS3 signal on two coax cables, TX and RX. Those cables will plug in to the DS3 mux. The mux will break out the T1?s respectively to the DSX-1 panel.

In general.....the T1 configuration is separate from the DS3 configuration. You can order a Muxed DS3 and request the T1s be optioned as ESF/B8ZS or D4/AMI. The company you order the circuit from should be able to configure the T1s either way.

DPC is short for Destination Point Code. It identifies your switch from other SS7 switches and is used to route calls to you as well as establish SS7 service to your switch.

One very simplistic way to think of SS7 is as if you were looking right at a person, face to face.

You see the person (T1 circuit) and you can talk to the person (SS7). If SS7 goes down you can still see each other, but you can't communicate with each other.

In most cases ISDN service or even standard T1E&M is the way to go, unless you are running a Central Office type switch (Lucent 5E or Nortel DMS-100).

If the provider can give you ISDN (PRI) service and your equipment has the capability to work with ISDN service, that would be the way to go only if your equipment can handle ESF/B8ZS circuits.

Afterall this is a DS3 not a bunch of T1 lines. Remember, your T1 orders are ordered to arrive to you on the DS3. When you order a T1, it's CFA (carrier facility assignment) is ordered on your DS3 and mapped on the DLR (design layout record).

Now you have a plan to follow that makes both technical and business sense. I strongly suggest that if you are ever faced with a similar situation..... that you make use of the free consultant services of to map a solution BEFORE you choose a provider and place your order. This will eliminate most of the potential frustrations encountered in this scenario.

Labels: , , ,


Anonymous Anonymous said...

Hello Michael

Can you explain compatibility issues between the MX2800 and DMS-100 T1 facilities?



4:51 PM  

Post a Comment

Links to this post:

Create a Link

<< Home