can any one tell me what the difference between digital telephone systems and analog and what are the advantages and disadvantges of both thanks in advance

Ha, you sound like some of my customers. I tell them that they are all digital but some manufacturers think that by using "digital" in the product name and printing it on everything they make will give them a sales advantage.

As far as real advantages, all I can think of is that most so called "digital" systems use one pair for each station as opposed to the much inferior "non-digital" which uses two. A single pair can be used because the audio signal is not analog however the disadvantage is that you cannot use standard T/R devices but there are ways around this with some systems.

So this is really just a design issue with no real advantage from one to the other.

-Hal





[This message has been edited by hbiss (edited March 27, 2005).]

There are two kinds of switching, Space Division (analog), and Time Division (digital). Voice communication is an analog signal. Analog switches do not modify the input signals. Each connection is like having your own road to drive on. Digital switches move numbers from one port to another using common connection just like all the cars sharing the same road. Voice (analog) must be converted to numbers (digital) to go thru a digital switch then converted to voice (analog) again. Just as paint by numbers (digital) images can never match photographs; there is a small distortion in the voice signal thru a digital switch. The ear does not notice this change. 56k modems cannot transmit from one analog port to another analog port of a digital switch. Analog switches can pick up electrical interference as noise. Digital switches are more resistant to noise. Just as you can still read a news paper if it has some dirt (noise) on it; digital switches will send a clear signal as long as the numbers get thru.

This has to be more than you wanted to know.

I think the industry stopped producing analog switches in 1975. If a salesman makes a comparison of thier product as its digital compared to the competitors analog. I would run away very fast. Saying a phone system is digital is like saying water is wet.
As a technology, analog is the process of taking an audio or video signal (in most cases, the human voice) and translating it into electronic pulses. Digital on the other hand is breaking the signal into a binary format where the audio or video data is represented by a series of "1"s and "0"s. Simple enough when it's the device—analog or digital phone, fax, modem, or likewise—that does all the converting for you.
Is one technology better than the other? Analog technology has been around for decades. It's not that complicated a concept and it's fairly inexpensive to use. That's why we can buy a $20 telephone or watch a few TV stations with the use of a well-placed antenna. The trouble is, analog signals have size limitations as to how much data they can carry. So with our $20 phones and inexpensive TVs, we only get so much.
Enter digital
The newer of the two, digital technology breaks your voice (or television) signal into binary code—a series of 1s and 0s—transfers it to the other end where another device (phone, modem or TV) takes all the numbers and reassembles them into the original signal. The beauty of digital is that it knows what it should be when it reaches the end of the transmission. That way, it can correct any errors that may have occurred in the data transfer. What does all that mean to you? Clarity. In most cases, you'll get distortion-free conversations and clearer TV pictures.
You'll get more, too. The nature of digital technology allows it to cram lots of those 1s and 0s together into the same space an analog signal uses. Like your button-rich phone at work or your 200-plus digital cable service, that means more features can be crammed into the digital signal.
Compare your simple home phone with the one you may have at the office. At home you have mute, redial, and maybe a few speed-dial buttons. Your phone at work is loaded with function keys, call transfer buttons, and even voice mail. Now, before audiophiles start yelling at me through their PC screens, yes, analog can deliver better sound quality than digital…for now. Digital offers better clarity, but analog gives you richer quality.
But like any new technology, digital has a few shortcomings. Since devices are constantly translating, coding, and reassembling your voice, you won't get the same rich sound quality as you do with analog. And for now, digital is still relatively expensive. But slowly, digital—like the VCR or the CD—is coming down in cost and coming out in everything from cell phones to satellite dishes.
When you're shopping in the telecom world, you often see products touted as "all digital." Or warnings such as "analog lines only." What does it mean? The basic analog and digital technologies vary a bit in definition depending on how they're implemented. Read on.

Phone lines
Analog lines, also referred to as POTS (Plain Old Telephone Service), support standard phones, fax machines, and modems. These are the lines typically found in your home or small office. Digital lines are found in large, corporate phone systems.
How do you tell if the phone line is analog or digital? Look at the back of the telephone connected to it. If you see "complies with part 68, FCC Rules" and a Ringer Equivalence Number (REN), then the phone and the line are analog. Also, look at the phone's dialpad. Are there multiple function keys? Do you need to dial "9" for an outside line? These are indicators that the phone and the line are digital.
A word of caution. Though digital lines carry lower voltages than analog lines, they still pose a threat to your analog equipment. If you're thinking of connecting your phone, modem, or fax machine to your office's digital phone system, DON'T! At the very least, your equipment may not function properly. In the worst case, you could zap your communications tools into oblivion.
How? Let's say you connect your home analog phone to your office's digital line. When you lift the receiver, the phone tries to draw an electrical current to operate. Typically this is regulated by the phone company's central office. Since the typical proprietary digital phone system has no facilities to regulate the current being drawn through it, your analog phone can draw too much current—so much that it either fries itself or in rare cases, damages the phone system's line card.
Perhaps the most effective use of the digital versus analog technology is in the booming cellular market. With new phone activations increasing exponentially, the limits of analog are quickly being realized. Digital cellular lets significantly more people use their phones within a single coverage area. More data can be sent and received simultaneously by each phone user. Plus, transmissions are more resistant to static and signal fading. And with the all-in-one phones out now—phone, pager, voice mail, internet access—digital phones offer more features than their analog predecessors.
Analog's sound quality is still superior—as some users with dual-transmission phones will manually switch to analog for better sound when they're not concerned with a crowded coverage area—but digital is quickly becoming the norm in the cellular market.
You may have an analog phone at home and call your next door neighbor with the same type of phone but you are still connecting thru a digital switch. You can buy LP's but the amplifier is digital.

[This message has been edited by gkar (edited March 27, 2005).]

If a salesman makes a comparison of their product as its digital compared to the competitors analog I would run away very fast.

That's exactly what I get sometimes from a prospective customer. We mainly sell Avaya and they will compare it to Panasonic. They'll say Panasonic is digital, it says so right on it. It HAS to be better. How come Avaya isn't digital? I then tell them what I said above and they look at me like I'm crazy.

-Hal

I think the partner is analog. It's simply using EKT's. The Panasonic KXT IS digital. The phones are 1 pair digital voice.



[This message has been edited by Coral Tech (edited March 27, 2005).]

Panasonic KXTD is digital KXTA is analog

Nortel makes proprietary phones with multiple lines that work with the DMS100 switch that are analog phones. These P-phones use 8khz ASK for signaling.

[This message has been edited by RedTail (edited March 27, 2005).]

Do not confuse electro mechanical with analog. Production of electro mechanical switching stopped in the seventies. Solid State analog switching was produced using varactors. All switching today may not be digital but all switching today is controlled by micro processors.

The difference is in the method of transmission. An "analog" transmission is in wave form while a digital signal is in 0s and 1s. Digital signals tend to be clearer and use much less hardware (fewer circuit paths) to transmit the signal. The EKT systems from the late seventies through the early 90s are analog as signal is still being transmitted in wave form.
That said, I do not know of any phone system manufactured today that is using wave form signalling. Even the Panasonic KXTA system is using digital signalling inside the switch. Why they decided to call it analog is beyond me.
The Partner is Digital, not analog.

------------------
Avaya Telephone Repair
Toshiba Telephone Repair

Are you sure? I am pretty sure the Partner uses regular anaglog signaling on the center pair ala EKT (electronic keyset) as opposed to digital voice transmission. The Panasonic KXTD actually has a true seperate analog port onb the center pins AND the digital phone work off pair 2.

See what I mean? Even WE can't decide what's "digital" and what is supposedly not.

But forget all that, other than what I mentioned above in my first post what difference does it make???

-Hal

thanks to everyone who posted all the info helped me out a lot

This information will be added in the Sundance Wire called: Bites of Information.

If you want your real name and Company name listed in the artical please edit a post with that info.

------------------
| Need a Telephone | Telephone Installers

It's been added:
https://www.telbroker.com/newsletter.htm

------------------
| Need a Telephone | Telephone Installers

I'm with Coral on this one, if the Partner is a true digital switch why do analog sets work on the station ports?

------------------
One stop Voice and Data Solutions VoIP

Not only that Mile but I THINK if you put a buttset on those pairs you hear the whole conversation on the phone. The Panasonic is totally different.

Because I can put analog phones on the largest PBX in the world does that make it a analog switch like the Partner?

I will say it again, Run away really fast from those people.

Of course analog ports on a PBX will be analog. I am talking about the digital and EKT sets. What I am sayig is that I don't think the the Partner system has digital phones ie...the coice is not transferred ala digital signal.

The Partner phone is a Hybrid. It uses analog signaling for the voice path=truer sound quality. Digital signaling for call setup and phone control= more features. Hence the 2 pairs.

Hence, it isn't a digital phone. It's an Electronic Keyset telephone or EKT not a DKT (Digital Keyset Telephone).

They ALL convert digital or electronic to anolog at some point, phone or ksu, or all you'd hear is beepedy beep beep. It's just a matter of where that converson takes place. There are no purely anolog systems that I know of being made anymore. Bottom line, electronic or digital you program features and options, pure anolog you wire them.

Krane,

I just emailed you....check your email

Walter

Gkar said:
"Because I can put analog phones on the largest PBX in the world does that make it a analog switch like the Partner?"

I will say it again, Run away really fast from those people.

No it is still a digital switch but those ports are analog. And the digital phones you hook up to the digital ports are digital... Partner does not have digital ports for the sets nor does it have digital sets....So the partner system is not..... again is not a digital system.......
The talk path on a partner system is the wb/bw pair the data and power for the set is the wo/ow pair... If you have a talk path on a seperate pair of wires it is not a digital system... with a digital system you have a data stream on one pair.... There are digital systems that use a second pair to power the phones... but do not use it as a talk path. Above posts have already answered the question "which is better"

Walter
Valentine Systems
25 years in business and going strong...

I think some of you are saying the same thing in a different way.

Hybrid/EKT systems do use digital signalling for setup, features, lights, and buttons, but the voice stays analog on a separate pair from your mouth through the switch to another phone or CO line. They use (typically) the blue pair for voice and the orange pair for signalling. This can roughly be compared to a 1A2 system, where the line buttons and lights are controlled by different wires than the voice.

Digital/DKT systems convert your voice from analog to digital inside the phone and transmit it as digital from the phone through the switch to another digital phone, or convert back to analog in the CO card. Analog phones (2500 sets) on these systems connect to an analog card that does the analog to digital conversion on the card before going into the switch. They only use one pair from a digital phone to the switch.

Hope this helps.

I think that's the best explanation anybody's gonna get.

But like they've said, it doesn't matter. I actually like the partner and even the old Vodavi starplus systems better than some digital systems (norstar, DBS). Only analog system I've ever worked with that I didn't like was ExecuTech. That system was no more than a 1A2 system with a lot less wiring.

I still use EKT's on my Tadiran in my house for crying out loud. No one said they were bad, just they are what they are.

Hey HBiss, can you explain what you mean about analogue needing two pairs a haven't come across that before?. I work on both Siemens and Alcatel systems and it is all single pair, whether it is a digital line or analogue line coming out of the PBX.
Same as our POTS service here is single pair as well.

Analog uses one pair for voice, it will use a second pair for data and can use a 3rd pair for OHVA (off hook voice announce) and there's a few systems that use the 4th pair (Merlin Classic comes to mind) but I don't know what it's for.
Digital can sent all the above information on a single pair.

------------------
| Need a Telephone | Telephone Installers

I said that because that is usually the case as test-ok explains.

I'm not familiar with Siemens or Alcatel. Does a one pair (T/R?) analog set have all the functionality (such as line buttons etc) as the digital sets or are they basically single line sets with no line appearances and you use hook flash and dial codes? This is all I have ever seen.

-Hal

Yo tok, I think that 4th pair was for the intercom.

Basically single line set with hook flash and dial codes.
They are Enterprise size PBX's that I work on, I think they concentrate on selling the digital side of things and leave the analogue ports/sets for basic phones, faxes and modems etc.

The Panasonic is Digital and analog. The keyset can use second pair for data and first pair for voice or it can use the second pair for data and voice, with digital sets. People want buzz words, people buy buzz words. People love marketing, even if they say they don't.
Why else would rational people pay 60 grand for a Chevy 1500 pickup with a welded on top, bunch of sound deadner and glued on plastic parts that Marketing call an
Escalade??

the ports on partners may be analog but internally the voice is digital for switching purposes, right ?

Nope. They are considered an EKT. Electronic Keyset Telephone. That analog center pair is controlled via digital means BUT it's still analog. The Panasonic Digital system uses seperate ports and pairs ie the digital phone is a true digital phone and the analog port is seperate.

1pair doesn't allways mean digital, time and space division PBX's have allways used a single pair. They process the call with a microprocessor ,the phones are analog .PBX Public Branch Exchange.just a small version of a C.O.

I remember the first time I saw a digital 1 pair telephone. ROLM was trying to sell a system to a large college whith multiple buildings and old BELL cables that were bridge tapped all over the place. We tried to tell the customer that he would have to recable the campus or dut out the bridge taps but the ROLM salesman got really upset with us. We recommended he get an engineer in on the project. The engineer traveled 3 hours for another meeting with the customer and when he found out the cables were all bridged he blessed the salesman out right in front of all of us and walked out.

------------------