POTS Dialup connection Vs ISDN

Posted on 2003-11-17
Last Modified: 2009-12-16

What is the difference between ISDN connection and a dial up connection using PSTN/POTS(normal telephone connection which uses analog technology in local loop) for Internet access?

1)Both service provider(ISDN and POTS) promises a bandwidth of 144 kbps.The desired answer is expected only in terms of effective bandwidth that we recieve and not the advantages of ISDN like several connections can be made simultaneously etc.

2)Is higher cost of ISDN connectivity justified? How in terms of effective bandwidth?

Thanks in advance
Question by:milanygandhi
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LVL 79

Expert Comment

ID: 9794373
Silly homework question...

Neither POTS nor ISDN can promise 144kbps.
Dual-channel ISDN = 128kbps. Period.
Analog POTS is limited to <56k per modem. Multiple modems *can* be "bonded" to achieve near 144k with up to 4 modems and 4 phone lines.

Is higher cost justified? That's all relative. Is a speed increase from <56k to 128k worth the monthly recurring plus the per-minute charges of ISDN? Is it as cost-effective as other technologies such as DSL and Cable, or even T1?

LVL 79

Expert Comment

ID: 9794407
In the interest of academic honesty, if this is a homework question, please remember to do your own research first. If you don't understand a concpet, then ask specific questions of your own.


Author Comment

ID: 9794766
Please note that this is not a homework question.  I want to decide normal telephone connection and ISDN connection for accessing Internet.
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LVL 79

Expert Comment

ID: 9796471
You are getting empty promises of 144kbps on analog POTS. It cannot happen.
You can, however, get 144kbps on G3 cellular service, possibly with a wireless feed, or DSL on your same copper wire as your phone.

LVL 79

Expert Comment

ID: 9806376
Comments, reactions, feedback???

Expert Comment

ID: 9827563
My feedback is lrmoore is kind of a jerk.  :)  I don't understand why people have to respond to a question sarcastically.  If you are so dang smart that you don't want to be bothered with a question like this, then don't answer it.

Back to the original question...

I have used both ISDN as well as dual channel 56k dialup and can definetly say that ISDN is the better option.  Depending on whether you are installing this service at a residence or at business will determine the cost justifications.  For instance, in a home scenario you can specify one of the channels as a voice port and it will drop from the internet if a call comes in.  Let me know if you have any other specific questions...
LVL 79

Expert Comment

ID: 9827739
Welcome to EE. As a relative newcomer, I don't think you should pass judgment on me and jump in calling people a jerk. That is not the best way to become a respected expert in any forum on this website.

If you take the time to look at my profile, I have been here for a very long time and have participated in literally thousands of questions. This question was written in the form of a homework assignment. If it was not an assignment, then perhpas the asker is a teacher and is just accustomed to phrasing questions that way. If you read closely the membership agreement for EE, you will notice the part about academic honesty. We are not supposed to answer obvious homework questions directly, rather guide the asker to either ask more detailed questions, or guide them to where they can get more information.

In this case, the asker politely stated that this really was not homework, and it was left at that.

I did take the time to answer the question anyway.
The facts remain.
-You cannot get 144kbps with either dual 56k POTS analog lines, or with dual-channel 64k ISDN (128k). I would challenge any provider that promises 144k with either technology.
-ISDN is much more expensive than a standard POTS.
- the value of the additional cost is only relative to the value that the individual places on the added speed. Is it worh $100/month extra to have an average web page load in 4 seconds vs 7, or to be able to download an MP3 in 10 minutes vs 20? Would it be cheaper to just buy used CD's?
It's all relative..


Expert Comment

ID: 9827798
Thanks for the welcome.  I wasn't trying to make any enemies, just merely stating that you could answer a bit more politely.  Just cuz someone asks a question that you may think is obvious doesn't mean that it's someone trying to get an answer to homework.  I believe it was you that started with the sarcastic response with your reply to the original question.

Also, I agree that you are not going to get 144k with either solution.  However, ISDN is not necessary much more expensive than standard pots.  This is dependent on various factors and the cost varies from different phone companies.  I would agree that it is relative to what you will be doing and your specific scenario.
LVL 79

Expert Comment

ID: 9827855
I hope that milanygandhi was not offended, nor took my remark so harshly. My intent was not meant to be demeaning, nor overly sarcastic. Trust me, we do get LOTS of silly homework questions posted here as I'm sure you'll come to appreciate over time if you stay with us.

Anyway, one more time -- Welcome to EE!


Expert Comment

ID: 9827898
no problem...understand i'm just looking at it from the perspective of a newbie to ee.  i have asked a couple of questions and the typical response that i've received have been demeaning answers where it didn't appear that the responder read my question in its entirety.  

thanks again.  
LVL 79

Expert Comment

ID: 9827969
Unfortunately, that happens. Some of the "experts" here can be quite arrogant. I hope I'm not one of them. With the fresh perspective from your view, I'll be sure to watch myself from now on because I don't want to be in that same class.

- Cheers, mate!

Accepted Solution

EjayHire earned 125 total points
ID: 10004349

Imho, ISDN is worth it if you are going to be online a lot.  A pair of bonded analog dial modems will get you 60-70% of isdn speed real world. If you have great phone lines and can see the CO from your driveway then you might make 80%.  What makes the biggest difference for me is the faster connect time with ISDN.  With an analog modem 45 seconds is a fast dial-till-surf time.  An Isdn call-authenticate-connect-surf is under 5 seconds usually, and with a good router (instead of just a modem on the PC) the delay can be so small you'd think you had an always on connection.  Because the ISDN connnect time is much faster you can do bandwidth on demand to only bring up the second B channel when you need it, instead of leaving it locked on all the time.

FWIW, I like the cisco 802 or 804 routers.  They are the same model internally with a built in isdn U interface, just the 804 has a built in 4 port hub  Both include POTS (telephone) ports so you can connect analog devices (Phone or fax machine) to them for use when one or both Isdn channels are free.  Both are under a hundred on ebay.

Hope that helps,
Ejay Hire
Ejay Hire at hotmail dot com

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