What type of line does Digital Centrex run over?

[edokid]

Hey everyone,

I work in telecom and I have a customer that has digital centrex service and is switching to analog business lines. They only have 2 digital centrex phones. I know the lines from the CO to their office is digital lines so analog needs to have new lines run. I'm confused with what the inside wiring looks like. I understand it's different but just for my personal knowledge, what type of line does digital centrex phone sets run off? It's not just normal copper lines? I'm going to have 2 analog lines installed to their demark, but it's from their demark to the 2 phone jacks in the office that I'm confused with what is there. Just wondering how a digital centrex line internally is different from a standard analog line. THANKS!

 

[paterson]

Digital Centrex, Analog Centrex, and Loop Start Analog lines(Analog Business Lines) will work on the same type of copper pair cabling. They are just different types of signaling requiring different types of end devices.

_______________________________________________________________

If you did not take enough time to get it right the first time...

What makes you think that you have time to fix it?

 

[kwbMitel]

I know the lines from the CO to their office is digital lines so analog needs to have new lines run.

Who sold you that line?

Both Digital and Analog run on the same facilities. In fact they can run on the same card and all that is required is a software change. Typically they run on different cards at the CO and all that is required is re-termination at the CO.

*******************************************************
Occam's Razor - All things being equal, the simplest solution is the right one.

 

[edokid]

Hey everyone thanks so much for your help. I actually work as a business partner for a Telecom company. We have a promo for analog business lines so I was migrating some customers who are on analog centrex over. This way it's just a billing change, they switch the analog centrex to analog business lines, and if they have phone hardware we get their interconnect to come out and change anything that is programmed to dial 9. Most customers on analog centrex don't dial 9 so it's an easy change.

A few customers we've done this change for, our provisioning team has rejected the change saying the customer is on digital centrex and that you can't convert digital centrex lines to analog business lines. They're saying we need to run new lines to the customer prem that are analog business lines, and customer needs analog wiring not digital internally, and then of course to replace their digital centrex phone sets with analog business phones.

To me that doesn't really make sense but since they're the technical ones I don't question it. That's why I posted here because I was curious what a digital centrex line looks like, but to me like you said it should just be a copper pair. If anything it may be that they don't want to make that software configuration change at the CO to change it from digital centrex to analog business lines...

Long story short, the customer I have has digital centrex 2 lines running to his office, and then 2 digital centrex phones. We tried to change him to analog lines and his interconnect came out and said he needs new hardware since it's digital centrex if we're going to analog lines which makes sense. However provisioning rejected it saying we can't change him to analog lines that we need to install new lines that are analog so that's where I'm confused!

 

[KE407122]

Analog Centrex - 1 line per wire pair.
Digital Centrex - Can have multiple appearances of the same DN or multiple lines and feature keys over a single wire pair.

If you are changing to analog you may have to use additional pairs to provide multiple 'line' capacity to each set. (eg. M9417 set can take two analog lines, M5316 Digital Centrex set could have many line appearances.)

KE407122
'Who is this guy named Lo Cel and why does he keep paging me?'

 

[edokid]

Okay thanks this is starting to make more sense. So when you say analog has 1 wire pair, you're referring mostly to from the demark to the CO? And digital centrex is the same, except it can have multiple line appearances over that single line since it's digital?

In terms of inside wiring would that be the same? Let me see if I have this correct:

Customer has 2 digital centrex phones. The lines running to those phones have 1 wire pair but can have multiple lines running over those, so if he pays for 2 Centrex lines, each of his 2 phones can use line 1 or line 2? Where as switching to business analog lines, using the existing wiring, each phone would have only 1 line like a normal house phone, and if they wanted to use multiple lines they would need additional wiring for that.

I guess what it boils down to, is if we take the digital centrex phones out of the picture, in terms of the lines from the CO to the customer demark and from the customer demark to the actual phone jacks, what is the physical difference between a digital centrex service vs analog business lines (not talking features just physical cabling) is there any?

 

[paterson]

No difference in physical cabling.

They are probably telling you to order new lines for demark so that the existing devices can remain working until a technician on site changes the device. Very common practice to have temporary dual service for a short time frame.

_______________________________________________________________

If you did not take enough time to get it right the first time...

What makes you think that you have time to fix it?

 

[edokid]

That makes sense, thank you so much!!!

 

[edokid]

Actually just an unrelated question since you guys know you're stuff. Whats the benefit of having analog centrex vs just a business line? If analog can only have 1 call on it why would anyone want that versus digital or just business lines?

 

[kwbMitel]

Think of Centrex as a VERY LARGE PBX. It has a lot of features common to most PBX systems.

Busy Lamps, Line Appearances, Transfer, Hold, Common Speedcalls, Ring Groups, Centralized VM to name but a few.

*******************************************************
Occam's Razor - All things being equal, the simplest solution is the right one.

 

[SYQUEST]

Digital Centrex and ISDN Centrex are very similar in that they use digital sets. The Digital Centrex set, usually Nortel on a DMS switch, is a proprietary phone. It only works on a DMS switch. An ISDN set can work with most ISDN services from all CO switches providing ISDN service.

Centrex service, be it digital, analog, or a combination can provide some features that other systems don't. Like a customer has multiple locations in one city or area, with Centrex the lines can all share common intercom between offices, call transfer, and other features just like a PBX system but the switch is in the CO. Since the calls are all "intercom" between offices, no useage charges. A lot of times you can get special rates for this type of set up too.

....JIM....

 

[edokid]

Thanks everyone that makes sense! I understand how Centrex works and the benefits it was more the difference with digital and analog. When you say ISDN I assume you mean analog? I know Centrex is an older platform, we don't even really sell it anymore as it's more hosted PBX now. I was just wondering more along the lines of why someone when ordering it years ago would have chosen digital centrex over analog centrex. Is it more just that because digital centrex uses those special phones they give more features and functionality where analog centrex would just be a plain phone?

 

[SNSSMIS]

CENTREX customers continue to use CENTREX to tie in all of the sites in the LATA with 4 digit dialing. both combination of digital and analog. Some sites have a PBX or Hybrid/KEY system. Others may have the M phones that privide the PBX, busy lamp features without the sysmtem on site.
The cost per line is around 17 per month verus a CO line that may be 25 per month. Also, with CENTREX, you can request assume dial 9 for the banks of lines reserved for the CENTREX group. Still some cost savings depending on the terms of the contract and how many lines you commit to.
Bottom line CENTREX it is still attractive to customers that do not want to provide on site equipment and have 99.9 - 100% up time.

 

[KE407122]

Yes, Centrex is like a PBX. Sometimes, in more ways than you like. There can be a blocking architecture.

A PBX can have a small number of trunks yet a large number of Sets. Centrex may work in your area the same way. You could have a large number of Centrex sets and actually a smaller number of PSTN's. If all your users tried to dial out at once some could not dial out. PSTN's are not normally provisioned 1:1.

Integrated Services Digital Network
ISDN- Usually translated as I Still Don't kNOw Or I Smell Dough Now is an older digital service. It is simply a Digital Dial Up data circuits that can be used for voice-video-data simultaneously. (2 services over a single wire pair)


KE407122
'Who is this guy named Lo Cel and why does he keep paging me?'