Follow Slashdot stories on Twitter

 


Forgot your password?
Close
typodupeerror
×
Communications The Internet Wireless Networking Hardware IT

You Don't Know Jack about VoIP 113

Posted by michael from the single-purpose-phone-lines-so-old-skool dept.
gManZboy writes "Phil Sherburne and Cary Fitzgerald, two senior technologists over at Cisco, have written an in-depth overview of VoIP for developers and the like (not for everyone who's ever used a phone). Like Queue's earlier You Don't Know Jack about Disks, this article covers the history, the basic technologies, how they work, and where they're headed. If you found the blog post yesterday lacking, check this one out."
This discussion has been archived. No new comments can be posted.

You Don't Know Jack about VoIP More

You Don't Know Jack about VoIP

Comments Filter:

  • inevitable (Score:5, Insightful)

    by scaaven ( 783465 ) on Tuesday September 21, 2004 @02:12PM (#10310848)
    voip will take over. Voice can be transmitted at such a low bandwidth, and all the cost to make a connection anywhere in the world is the cost of your ISP. I think they have them, but you need to have some sort of program always listening on a port from your IP, and transfer incoming calls to a usb connected phone that rings. Then you'd have all sorts of spam bots calling everyone's IP, so you'd have a list of approved incoming IP's or a numerical code that allows your call.

    • Re:inevitable (Score:2, Interesting)

      by Nos. ( 179609 )
      VOIP will, especially cellula service. At least once we get more wireless access points happening. Finally get some real point of prescence happening for voice, messaging, office access etc.

      One other thing. I prefer VOIP services that offer a hardware box where I can plug a regular phone in. Especially since then I can use my cordles, or whatever handset I prefer. Even better if I wire it in when the phone line enters the house, then I don't change anything else, and every phone in the house in now
      • yeah. some sort of box that plugs into your network and your router knows to forward the voip ports too. then the box has actual phone plugs for you phone and it makes a "call" when it recieves a voip connection.

    • Maybe (Score:5, Insightful)

      by paranode ( 671698 ) on Tuesday September 21, 2004 @02:24PM (#10311013)
      and all the cost to make a connection anywhere in the world is the cost of your ISP

      Unless you're one of the unlucky who has to use a DSL provider which requires you to pay for a landline to get said DSL service. Then you're stuck in a bit of a pickle. Hopefully that will change, I seem to remember hearing about laws regarding that problem.

      • Re:Maybe (Score:3, Informative)

        by Florian Weimer ( 88405 )
        Unless you're one of the unlucky who has to use a DSL provider which requires you to pay for a landline to get said DSL service. Then you're stuck in a bit of a pickle. Hopefully that will change, I seem to remember hearing about laws regarding that problem.

        In Germany, you can get a DSL line from the big telco ex-monopoly, and quality Internet service from a local provider. It's a bit like B-ISDN, as it was originally proposed (but, of course, without any bandwidth and latency guarantees), only with IP s

      • Re:Maybe (Score:2, Interesting)

        by bungeejumper ( 469270 )
        I don't like cable modem service, so I deliberately chose DSL. Of course, that means I need to get the POTS service...but, I've gotten my landline service down to 8.44$/month with the "metered" service package. And I make those 8$ up by receiving unlimited calls on it (instead of using my cell phone airtime), so it's practically free.
    • so you'd have a list of approved incoming IP's or a numerical code that allows your call.
      Or better yet: pgp keyid, which is then used as a key into a reputation database...
      • > used as a key into a reputation database

        Controlled by?
        • > used as a key into a reputation database

          Controlled by?

          Whoever you want. It's your phone, after all.
          • > Whoever you want. It's your phone, after all.

            I misunderstood "reputation database" to mean a comprehensive list of other companies' "reputations" that would be shared between subscribers.

            It seems a little unrealistic to me to expect every single customer to enter every single IP/phone# they think might be calling them.

            • It seems a little unrealistic to me to expect every single customer to enter every single IP/phone# they think might be calling them.

              Of course.

              In practice, you would probably delegate, maybe through the same Web of Trust that you use for authentication, or maybe not.

              For example, you get a call from someone who you have no previous experience with (it's someone you haven't entered in your local database), and you've told your phone that if it just has no clue who someone is, go ahead and ring. (Perhap

    • No, not inevitable. Obsolete (Score:5, Insightful)

      by Animats ( 122034 ) on Tuesday September 21, 2004 @02:37PM (#10311134) Homepage
      Cellular providers have had flat-rate long distance for a while now. That's what's really putting pressure on the wireline carriers. Now we're starting to see flat-rate long distance from the wireline carriers. Soon, at least for U.S. domestic calls, there will be no price advantage for voice over IP.

      Internationally, though, voice is still a cash cow. That may last a while longer.

      Voice over IP is more of an advantage for companies with elaborate internal telecommunications infrastructures. The VoIP gear is cheaper.

      • Sorry, no mod points today or you'd get +1 Insightful.

        In more developed/affluent areas, the LECs are now offering fixed-price bundles that compete very well against separate broadband/VoIP/LD packages from separate providers.

        Where this makes a differences is in outlying suburban and rural markets where the CATV provider is often the only choice for broadband, and there's no local telco competition. I live in such a place, and although I'm served by Verizon, my pricing structure and options are very dif

      • Soon, at least for U.S. domestic calls, there will be no price advantage for voice over IP.

        My packet8 account costs me $20.00 a month. I looked for flat rate longdistance POTS and it was at least $65.00 a month. That sounds like a bit of a price advantage to me.
      • From the article: "both data and voice could be carried on a common, packet-based network. This would simplify management by reducing the number of networks to manage, and lowering network facility and hardware costs."

        This is total bullshit. When you integrate IP services into the core, your IP core suddenly goes from being a best-effort delivery system with maybe some packet priorization, simple and easy to understand, to a system that has to implement QoS
        and tagged switching. In addition to the added c

    • Re:inevitable (Score:3, Insightful)

      by TwitchCHNO ( 469542 )
      Yes & no.

      Voice over ATM & Voice over IP do have alot of potential for telcos & backhouling. Both VOIP & VOATM offer much of the same benefits - call routing, dynamic packet switching. The last mile barrier will prevent VOIP/ATM from completely replacing POTS, especially in rural areas.

  • Test your connection... (Score:5, Informative)

    by fiji ( 4544 ) * on Tuesday September 21, 2004 @02:13PM (#10310857)
    Before you waste time trying to get VoIP (or paying for VoIP from a provider) going it is worth testing your connection to see if it can support VoIP calls at a reasonable quality. You might want to test your line at various times during the day... I get crappier calls in the evening.

    Anyway, http://testyourvoip.com/ [testyourvoip.com] provides a decent free testing serice just using a web browser.

    -ben

    • Re:Test your connection... (Score:5, Insightful)

      by Nos. ( 179609 ) <andrew@@@thekerrs...ca> on Tuesday September 21, 2004 @02:31PM (#10311086) Homepage
      Some other things to think about before switching completely over to VOIP... what happens during a power outage? You're POTS line will still work, but your VOIP probably won't, unless you are providing backup power. Not to mention your *11 services (411, 611, 911) may or may not work depending on your service provider. Also, even if they do not connect you, they may not be able to locate you. One of the best feature of 911 is the ability to locate the source of an incoming call in case the caller is unable to speak.

      • Re:Test your connection... (Score:4, Interesting)

        by Vancorps ( 746090 ) on Tuesday September 21, 2004 @02:38PM (#10311147)
        This is really what's slowing down adoption of VOIP in the home. Here at the office we currently use Cisco VOIP but we're switching to Televantage because Cisco's sucks so bad. Amazing how many features weren't well thought out. I mean, it takes 5 steps to transfer a call to voicemail.

        At any rate, I wouldn't think it would be a problem for VOIP providers to integrate with 911. They have the address of all their customers, seems like it would be trivial to have a 911 operator send out the request and an automated response would reply with the address. That would solve the problem of not being able to find the person trying to call.

        As for a power outage, we had one recently and our cisco poe switches kept all the phones up so most of the building had no idea the servers were no longer receiving power.
        • At any rate, I wouldn't think it would be a problem for VOIP providers to integrate with 911. They have the address of all their customers, seems like it would be trivial to have a 911 operator send out the request and an automated response would reply with the address.
          I've done some work for a VOIP service provider. The way their system works, they don't know your current location. Sure, they know your home address, but with their setup, there's nothing to say I didn't take the box to my friends place,
          • A basic ups would keep your standard cable connection up during a power outage. I will admit I had not considered the ability to take the VOIP kit offsite. That would definitely make it more difficult. In that case I have no idea how to approach that without requiring every ISP to maintain a current database of ip/address matching. That could be trouble.
          • That may work in an office environment when the phones are hooked up to the switch, but what about at home, when your VOIP is over cable or phone line? No power, no dial tone.

            That is most certainly not the case. Phone lines and internet access often work during power outages as long as you and the ISP/telco have backup power for your equipment.

        • Cisco IP Telephony (Score:2, Informative)

          by csmacd ( 221163 )
          Sounds like your system is not set up correctly. You should be able to transfer a caller to (extension)#2 and send the caller to (extension)'s voicemail. There is another config to allow prepending a digit or * to the (extension) to send to voicemail.

          As long as the phones and a voice gateway have power, the survivability feature should keep some voice services active in the event of power failure.

          911 works well, as long as there is a gateway with a POTS line at each site. Otherwise, you've got to do t
          • Unfortunately we don't have control over the way it is configured. We get some interesting issues with echos and the likes despite the pipe not being near capacity.

            As for the 911 stuff, our phones allow for callerid so 911 can just call us right back if there is a problem. I'm not sure but presumably if they have the phone number then they have a physical address. Of course another poster mentioned the ability to call offsite, such as at my boss's house. In such a situation that idea would not work.

            All t

            • Cisco hasn't been concentrating on producing telephony features for the past 50-100 years like many of the pbx manufacturers out there have been and it shows in their product. I suggest you look at the Avaya [avaya.com] ip products and the Telrad [telradconnegy.com] ip products. Both can do more(and have more features) than the Cisco for a lower price.
              • > I suggest you look at the Avaya ip products and the Telrad ip products. Both can do more(and have more features) than the Cisco for a lower price.

                We currently use Avaya to support our Definity boxes that are getting pretty old. We were interested in moving to VoIP and spoke with Cisco reps so far, but I was only mildly impressed. Have you used the Avaya VoIP system? Did you see any major drawbacks to it?
      • Sounds like a config problem. For our Cisco system, you just transfer to *+extension to go directly to the extension's voicemail. There was no special configuration to do that.

        We're rolling out to 21 sites (400 phones) and have had only a couple of small issues so far.

        Jason
      • If I have a power outage I use my cell phone. Or go out onto the street and use a payphone. Or use a neighbours regular phone - whatever, if I need to make an emergency call I can.

        As for 911, they have my home address (and will route your call to the appropriate response center) but yes you will need to provide your location to the operator. Personally I don't see that as being a big problem, but then I've only had to call the emergency services twice and both times I could speak just fine (and co-incident
      • > ...what happens during a power outage? You're POTS line will still work, but...

        The last time the power went out in my neighborhood (in downtown San Francisco), the POTS line went completely dead. The cellular network remained up, however...

        Just because your incumbent telephone provider can light up the power line on your telephone system with a separate power distribution system does not mean they actually do so.
        • Actually it sounds like a common event caused both outages as POTS carriers are REQUIRED to have backup power for their equipment to supply phone service even if the power goes out. My guess is a pole or two were brought down by something and it took out power and phone service at the same time.
          • + POTS carriers are REQUIRED to have backup power for their equipment to supply phone service even if the power goes out

            Yeah, I know what they're required to do. Who's gonna make 'em? Seriously.

            (I know where the failure was in this latest power failure: it was in the substation in the Mission district. My central office is way the hell over on the other side of Twin Peaks. SBC is clearly not doing what they are "required" by law to do. Hold on while I call the cops... they say they'll send someone a
            • How about give the info to the PUC which has the ability to levy fines and pull licenses. If they aren't providing emergency power to their CO then they are endangering lives, the regulations are there for a reason.
              • > How about give the info to the [CPUC]...

                Wow, wouldn't that be a good idea? I'm sure an investigation into that will go right to the top of the stack investigations already underway into how SBC is in violation of the regulations. Why is it so hard to understand that SBC can ignore the regulations and get away with it because the power of the CPUC has been horribly emasculated by cronyism and years of underfunding.

                > soap, ballot, jury, ammo...

                soap, ballot and jury didn't work. where do i go to
                • > soap, ballot and jury didn't work.

                  So you have already made a public outcry about it, voted on the issue, and taken them to court?
                  • Why yes, as a matter of fact, we have... and it didn't work. So, again--where is the lawful contract that authorizes the spending of ammo on the problem? Or does the issue actually require more nuance that a cheap epigram?

                    (Sorry, man. People telling me I need to arm up if I don't get my way through the judicial process really push my hot buttons. I'm just gonna shut up about this now.)
                    • > where is the lawful contract that authorizes the spending of ammo on the problem?

                      It's not a lawful contract, but "When in the Course of human events...*" would generally lead to violent revolution. Now you just need to define when "it becomes necessary." If it isn't something that warrants political revolution, you're stuck with suffering with the problem or suffering with the consequences that arise from doing what you feel you must.

                      > People telling me I need to arm up if I don't get my way thr
      • what happens during a power outage?

        Same thing as my cordless phones over POTS. They have a battery in the base and a battery in the handset. Hours of use in a power outage (though the answering machine functions are disabled).

        My porn still flows when the power is out. The CO is on battery backup, and so is my PC, DSL modem, router, and a few other desk accessories. I'm not sure 911 service is as important as porn, but I think I could still spare some space on my UPS for it.

        And all VoIP providers I k
      • If you look at the article's figure, the VoIP they're talking about isn't the same VoIP that has 911 issues. They're talking about POTS lines connected to an IP network instead of to a switched network; it's only IP once it gets to the phone company. This is the system that, IIRC, British Telecom is considering, but it's different from Vonage and such, which uses IP between the phone and the provider and sometimes has problems with 911.

        Really, the term "VoIP" ought to be replaced with a bunch of more speci
    • On the page:
      > please do not run any other applications on your machine until the testing is complete.

      So, if I use VoIP, I have to shut down everything on my PC before making a call (assuming the traffic comes through the PC, I know there are IP phones)?

  • Oxymoron (Score:5, Funny)

    by StevenHenderson ( 806391 ) <stevehendersonNO@SPAMgmail.com> on Tuesday September 21, 2004 @02:13PM (#10310861)
    have written an in-depth overview of VoIP

    This is a great statement to read while eating some jumbo shrimp.

    • This is a great statement to read while eating some jumbo shrimp.

      While parking in the driveway, or driving on the parkway!

  • Jacking in (Score:3, Insightful)

    by Doc Ruby ( 173196 ) on Tuesday September 21, 2004 @02:15PM (#10310889) Homepage Journal
    What, indeed, do we know about Jack [quicknet.net]?

  • Which service is better? (Score:5, Informative)

    by exhilaration ( 587191 ) on Tuesday September 21, 2004 @02:16PM (#10310900)
    If you're in the market for a VOIP service, Geekbooks [geekbooks.com] did a pretty decent comparison of different services. Does anyone have any other links?
    • The only one I think is a valid choice is a href="http://broadvoice.com/>broadvoice

      they openly support and encourage you using linux and asterisk with their service. Going so far as to offer a really low cost version of their service to use with Asterisk+linux (and any 3rd party device)

      That fact alone makes me choose them over every other provider on this planet.

      They do not atempt to lock me out of my property by locking the device. No other VoIP provider will do that... .yet.
    • BroadBand Reports [broadbandreports.com] has a huge listing of reviews of VoIP providers.

    • One I didn't see in this list or the comments is Lingo [lingo.com]. I just signed up for them, but I've made a few long calls and have had no problems with them. Their tech support seems to be in India and I've had a few problems getting useful information out of their tech support (both inaccurate information and hard to understand accents). They initially told me to open ports 5060-5065 on my firewall, and what I needed to open was 1024-1027 to get my VoIP "link" light.

      Other than that, I've been happy with them.

  • What we want from Pa Cisco (Score:1, Interesting)

    by Anonymous Coward
    Last time I talked to Cisco they wanted about 75k (in USD) for a solution which had the main selling points of user login/call routing. ooooo!

    Still no phone2phone encryption!

    The unslient majority wants:
    - video phones
    - encryption
    - Cell+Wifi in one device with auto switch over
    - Server software that runs on Linux for those of us that like a standard back office.

    • Re:What we want from Pa Cisco (Score:5, Informative)

      by jaymzter ( 452402 ) on Tuesday September 21, 2004 @02:23PM (#10310997) Homepage
      Your comment sounds pretty interesting, since you seem to know what you want, but apparently haven't looked anywhere other than Cisco.

      Avaya's IP telephony products provide your encryption, Cell+Wifi with auto switch over, and my favorite, all the servers run GNU/Linux! No video phones yet.

      I hear they're really expensive, but I really don't have any clue as to that, I just fix the stuff.
      • Here here. It annoys me immensely the way Cisco trumpets their own solutions as "the way things are". Their bias is stunning. This results in a swarm of CCNA-folk who are the biggest PR machine you've ever seen.

        Granted, what Cisco makes tends to become the standard (largely due to the marketing spin mentioned above), however their way of going about it reaks of Gates' "the road ahead" tripe ...

      • We have an Avaya system where I work, and I would not recoomend it to an enemy, much less a friend. We have had nothing but trouble with it, and it hasn't gotten any better over the last year.
    • >Server software that runs on Linux for those of us that like a standard back office.
      like asterisk [asterisk.org]
      It supports many VoIP standards, pots, BRI, PRI, etc...
    • -The unsilent majority of users want those things.

      From a network administrator perspective, the idea of video phones is a shitty idea. a standard G.711 call is 64k of data.. how much back room capacity would you need to add to do video phones? especially site to site? all it does as give the exec's at companies the ability to point to the phone and say to their buddies, "Look at this, its cool!" It adds no business value. Yet Cisco pushes it very hard as a new feature.

      encryption would be nice, for

      • Videophones don't have to use a ton of BW over a G.711 call. Worldgate [wgate.com] [disclaimer: I work for them] and Motorola will be selling a videophone (Ojo) that works well at a steady 30fps over cable or DSL connections, at total bandwidth (including overhead) of 100Kbps (dsl) to 150Kbps (cable), audio and video. A G.711 (20ms) audio call is 64Kbps data, plus around 16Kbps overhead for around 80Kbps total. Don't knock visual and non-verbal communication until you've tried it, even ignoring people who are hearing-i
  • ...is here [acmqueue.org]!
  • Not just because of what Cringely said, but my phone works in a power outage, and still sounds way better than cell, for example. http://www.pbs.org/cringely/pulpit/pulpit20040624. html
  • I knew Jack.
    He's actually kinda friendly.

  • One problem with VOIP (Score:3, Interesting)

    by wiredog ( 43288 ) on Tuesday September 21, 2004 @02:41PM (#10311176) Journal
    How well does 911, or your local countries' equivalent, work with it? When you dial 911 from a voip phone, does it report the location of the phone, or the billing location of the phone?
    • How well does 911, or your local countries' equivalent, work with it? When you dial 911 from a voip phone, does it report the location of the phone, or the billing location of the phone?

      Your standard land line only reports the address the telco has entered in for a phone number. For residental this would just be the billing address. The diffrence is the fact that these land lines are fixed and generally don't move about too much. Not to say it never happens, it's possible to hook up the wrong wires to

  • That's Not In-Depth (Score:2, Insightful)

    by chemman ( 762023 )
    Wow. As much as that tells you something about VoIP it is mighty far from in depth. Entire books are devoted to nothing but QoS and H.323. You don't know anything if you don't know these.
  • I hereby order Phil and Cary to cease and decist using our trademarked phrase "You Don't Know Jack" to title their articles. We have been using this phrase for over a decade. Please see our website [jellyvision.com] for more information.

    Sincerely,
    Jellyvision, Inc.

  • Mine isn't. Well, it is for general usage, but my DSL is down for one reason or another a few hours every month. I've never had a cable modem but if it's anything like my horrible spotty Adelphia digital cable (which seems to be out a few hours a week, and has constant lags and glitches) I would expect the same.

    Neither of these problems is so bad, but if a DSL glitch meant I couldn't use the phone either I would really be up shit creek. (I suppose most home VOIP users would also have a cell phone, but w
  • ENUM. <snip> ENUM calls for telephone numbers to be written DNS-style, rooted at the domain e164.arpa. So, 1.212.543.6789 becomes 9.8.7.6.3.4.5.2.1.2.1.e164.arpa. Interestingly, each digit is treated as a subdomain. This allows ENUM to ignore the nuances of country codes, city codes, etc. that vary broadly worldwide. When this address is queried, the DNS can return a specific IP address corresponding to the telephone number, or it can return a rule for rewriting the original number into some other for

  • BANDWIDTH is not free (Score:3, Informative)

    by vpreHoose ( 587524 ) on Tuesday September 21, 2004 @03:45PM (#10311991)
    Where every Cisco VoIP system falls down is on the ammount of bandwidth required to support VoIP. From a telco operator perspective (voice or data) your greatest operational expendature is your bandwidth. Using IP or SIP costs you far more in bandwidth than is economic (when compared to alternatives). Yes you can multiplex voice and data but that takes even more bandwidth than doing it seperately! GSM is probably the most efficient way to carry voice over a digital channel. Does very well at 22kbit/sec. You even can do voice over GPRS at 33kbit/sec (the latency sucks, but you can do it). But try running a SIP session and it simply doesn't work. The protocol to establish the session and the overhead cannot be done on a low bandwidth channel. VoIP makes sence only when bandwith is free, but in the real world it isn't and the commercial imperative is to make the most of it.

    • Re:BANDWIDTH is not free (Score:2, Informative)

      by Anonymous Coward
      Check
      this out [voip-info.org]

      GSM typically takes about 13k per/call. Not to mention there are other protocols besides SIP. For example, IAX2 is wonderful. You can also "trunk" the calls to lower the TCP/IP overhead.

      G.711 (ULAW) typically takes about 64Kbps, which would be comparable single channel on a DS1/T1. With GSM, I can now fit over four calls in that same channel. How is this worse? I run SIP everyday, and did does work....

      http://www.telephreak.org [VoIP hackers]
      • Yes, you are right the Full Rate GSM codec operates at 13k. The bearer over the air is still 22k though. The AMR codec used for GSM and 3G networks is even more efficient, and can dynamically adjust the bitrate, and can operate on an 11k Half Rate bearer. It is also standardised as a code for use over the Internet by (I believe) the IETF.

  • VoIP Services vs. Your Own Network (Score:3, Informative)

    by chia_monkey ( 593501 ) on Tuesday September 21, 2004 @04:14PM (#10312312) Journal
    First off, I found the article kinda ho-hum (yeah, I read it...what was I thinking RTFA?). I've come across better articles on the net from such odd sources as USA Today and such. I will admit though that the last page had a few things that made me go "hm", in particular how they remind us that monitoring this system will cost a pretty penny.

    I've been doing research for a client that is wanting a VoIP/call center solution. When I started, it was fairly simple. Looking at the different services offered (Vonage, Broadvoice, Broadvox, Packet8 looking like the best solutions so far) and then I went to look at Cisco gear and see what it would be to set everything up yourself. And then I looked at some IP PBXs from 3Com, Avaya, Siemens, and Zultys. You know what guys? We've got quite a load of solutions out there for someone who wants VoIP. And these were all hardware-based...I didn't even bother looking at software-based solutions.

    I'm finding this whole VoIP thing to be just as interesting as WiFi...a wild new market with everyone trying to establish a foothold (remember the dotcom days with everyone trying to grab as much marketshare as possible?) and then weather the storm and see who survives. Interesting indeed.
    • < shameless plug >

      VoIP Call Center software? Have you tried www.inin.com?

      < /plug >

      Seriously, I've been working on this stuff for over a year, and every day I find just one more reason VoIP is going to "take over the world." When you add in the possibility of obtaining SIP lines rather than trunks, you can end up with extremely flexible, reliable and inexpensive setups and combine that with software based implementations. Add in the equation software based media processing, such as Intel's
  • Sweet so when my city will have 100% wireless coverage i could use my PDA to do VOIP basically for free. So in the far future we could all use those star trek chest thingies to communicate for free. Cant wait for the spammers to call me about penis enlargement pills. Captains log, earthdate december 14 2040 microsoft has a new discount on penis enlargement pills.
  • Skype [skype.com] Is working very well for me. Free, VERY high quality calls to other people who have the program installed, and cheap, local rates to any land line/cell phone in the world!

  • Time to detract again (Score:3, Interesting)

    by Ih8sG8s ( 4112 ) on Wednesday September 22, 2004 @10:30AM (#10318319)
    I wrote a post some time ago about how I thought VoIP was not ready for primetime. I was subequently trashed by a self-affirming moron and rated down. Whatever.

    Voice communication relies on time sensitive delivery of very small bits of information.

    IP networks are designed to deliver large gulps of information in a non so timely fashion. Wht I mean by this is that in an IP network, equipment will deliver information as quickly as it can, but there's nothing the 802.x quite of protocols which inherantly facilitates predictably timely delivery of data. Timely delivery is governed by network and infrasturcture "health". Sure, there's QoS, but that ultimately gives very little benefit unless the network is under heavy load anyways, in which case, VoIP is a bust regardless.

    Conversations can seem decoupled. Calling someone 1/2 mile away can introduce the latency that can be expected when calling overseas. It doesn't feel "like a phone" to many end users.

    Jitter, latency (huge), and the general difficulty of "simulating a telephone" over IP services is what will prevent VoIP for taking hold until several generations of technology and a generation or two of home connectivity methods is introduced.

    Contrast ATM networks, which are designed specifically to deliver small bits of information very quickly. These networks are ideal of VoIP.

    Poeple don't have ATM to their houses, they have DSL or cable services which offer NOWHERE near the reliability of a typical voice network.

    Someone can fairly realistically expect 1/2 of a building to be blown to pieces, while a phone in the other half will work. This is how reliable voice networks have been.

    Within a company on a controlled LAN, VoIP can work because you have some control over the quality of the service. To the home, we are not close to being ready.

    I've implemented VoIP switches since their initial introduction, I have spoken at international conferences on the merits and pitfalls of VoIP. I'm not trying to toot my own horn, I'm just saying.... I've used and abused these switches, phones and protocols, and I find them lacking outside tightly controlled environments. Across a vendor's backbone? Sure, no problem. Will I use it exclusively in my home? No freaking way.
    • "Poeple don't have ATM to their houses, they have DSL or cable services which offer NOWHERE near the reliability of a typical voice network."

      Most DSL runs ATM cells as a low level protocol. If they had their shit together, the DSL providers would have used this to their advantage instead of installing equipment that, even when it does support telephony, packets up voice calls and sends them over the same ATM PVC as the rest of your traffic. Talk about missing the point.

      The cable folks have their own, no

Slashdot Top Deals

"You know, we've won awards for this crap." -- David Letterman

Close