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Difference between digital phone and VOIP

Discussion in 'Security Alarms' started by JoeRaisin, Jun 13, 2007.

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  1. JoeRaisin

    JoeRaisin Guest

    Anyone know the specifics?
  2. Anders

    Anders Guest

    Short answer: Two names for the same thing.

    Long answer: VoIP is one form of digital phone service.
    Most "Digital Phone" offerings use IP and moves the data over
    your regular Internet DSL/Cable/Fiber connection, so that makes
    them VoIP by definition. Digital Phone Service *could* also mean
    it uses a separate, dedicated channel and/or a different protocol,
    but that's not common.

    So in most cases the issues are exactly the same ;
    - Power backup (if the cable/DSL modem and/or router is down,
    the phone line goes with it)
    - Latency/quality (it's a LOT better today than a couple of
    years ago, but can still cause problems for control panels)
    - User interference (users mess with the router, unplug wires,
    change service..)
    - Reliability (Internet Service Providers frequently cut off
    service for hours at a time to do maintenance or upgrades)

    If you hook up burg systems to VoIP/Digital, make sure both you and
    the customer understands the limitations, or you will both be very

  3. tourman

    tourman Guest

    Ain't that the truth ! If a client comes to me for a new installation
    and he has VoIP, I simply won't do it. If he changes later without
    consulting me, he signs the liability of exclusion (up on my website),
    or he finds another supplier - no exceptions!

    The few VoIP installs that I have chosen to make work have all been
    set for automatic daily tests. The daily reports on these systems I
    watch like a hawk, and most will check in ok with the station about 5
    days out of 7 successfully. The other two days...who knows.

    I'm pretty hard nosed about this part of our business. Unless a
    customer is serious about his security, I don't want his business
    (besides, I'm also "cherry picking" these days - not looking to buy
    troubles) VoIP is not yet IMO adequate for the job - maybe one day,
    but not today. Besides, there are IP connection devices that are both
    here now, and being developed, that promise reliability in the

    Personally, I'll wait until then......

    Home Security Metal Products
    Ottawa, Ontario, Canada
  4. Doug

    Doug Guest

    I could be wrong but I think that the difference is that cable digital phone
    providers use their own cable infrastucture, while VoIP uses the public

  5. Frank Olson

    Frank Olson Guest

    I think you may be closer to the truth. I've had several customers
    switch to Shaw's Digital Phone... With no problems on the alarm end
    (and that includes downloading the panels).
  6. Personally, I'll wait until then......


    Have you looked into any of the communications
    systems specifically designed for IP?


    Robert L Bass

    Bass Home Electronics
    4883 Fallcrest Circle
    Sarasota · Florida · 34233
  7. JoeRaisin

    JoeRaisin Guest

    But why does (Cable systems) digital work and VOIP has so many problems?

    We don't have any problems with DSL (assuming filters are properly
    applied) and as the name implies - that's digital also.

    The downloader guys at CS are griping about not being able to hit
    digital phone customers - but these are the same guys who want a tech to
    go out to a site because the customer keeps answering the phone (they
    don't bother to talk to the customer and explain anything, they want a
    tech to drive out and do all the talking). They claim there is no
    difference between the cable company's digital phone service and VOIP

    I've tried to google it but all the explanations are vague and geared
    towards selling the product.
  8. tourman

    tourman Guest

    Only in a cursury fashion to be quite honest. I am working closely
    with a small development company in the process of designing an IP
    communication unit called Lobenn. At the moment, they are going
    through the lengthy process of getting ULC approval. I am one of
    several alarm companies they interface with for information, trialing
    equipment, and (in my case) the loan of alarm panels.

    It would appear to be a decent unit; however, it will require a
    specialized receiver at the station to transfer signals to the regular
    receivers, so this may turn out to be somewhat of a "chicken and egg"
    scenario. Big stations don't move too quickly, so it remains to be
    seen about the "buyin".

    I'm taking a "wait and see" approach to this whole thing, since I
    don't want or need technical problems of that nature haunting me and
    my clients.

  9. Im taking a "wait and see" approach to this
    Since I deal primarily with DIYers, I get more
    calls from folks who are interested in experimenting
    with new technology. I'm always on the lookout for
    ways to handle things like VoIP, TCP/IP reporting,
    etc. I expect we'll see a lot more development in
    that area as the sunset clause approaches.


    Robert L Bass

    Bass Home Electronics
    4883 Fallcrest Circle
    Sarasota · Florida · 34233
  10. Doug

    Doug Guest

    I think that the cable systems digital service is closer to traditional
    phone service than VoIP, it may be that it just uses a different medium
    (cable instead of copper pairs) to transmit the local part of the call from
    the subscribers premises to a central office. With VoIP, everything is
    transmitted over the internet and problems arise because of varying speeds
    in which the packets are transmitted and received. I'm just speculating
    since I don't really know the answer. (RLB-insert stupid comment here).


  11. But why does (Cable systems) digital work
    There seem to be two problems that affect
    signaling over digital lines. First is latency,
    the time taken for a packet of data to be sent
    travel and be received. The grerater the
    latency, the more likely that the receiver will
    decide the data is invalid. Some systems
    are simply faster. However, even the fastest
    ISPs can sometimes bog down during peak
    usage hours (such as when Frank parses my
    website... :)).

    Another problem has to do with the codecs
    used by the VoIP provider. Codecs convert
    analog sounds into digital data and back.
    Some are very effective at handling DTMC
    (Touchtone) codes such as are used by
    Contact ID. Others are not. Obviously, if
    you are using CID you'll want an ATA* device
    that handles DTMF well. Many of the ATA
    devices which handle FAX machines well
    are also good with alarm signals.

    *ATA = Analog Telephone Adapter.


    Robert L Bass

    Bass Home Electronics
    4883 Fallcrest Circle
    Sarasota · Florida · 34233
  12. Matt Ion

    Matt Ion Guest

    The catch with that, at least in residential, is that they still depend
    on the reliability of the internet connection. Extended service
    outages, customers mucking with cable/DSL modem hookups, etc. are still
    just as much a concern.
  13. Jim

    Jim Guest

    I also believe you're right.

    Here, we have Cablevision. I've got dozens of people using their cable
    telephone service. They don't call it VoIP or Digital telephone. They
    refer to it as Optimum Voice. At a meeting they did say that they are
    required to provide for other companies VoIP services, such as Vonage,
    but they said that their service had dedicated bandwidth while the
    others were allocated a narrower bandwidth which could vary depending
    upon usage.

    I've had some problems with downloading, but only with a couple so

    As far as I'm concerned, VoIP is working here. But .... I still have
    my clients sign a waver.
  14. tourman

    tourman Guest

    Yes, for sure ! Customers messing around can screw things up big

    Also, these interface devices cost significant dollars and in most
    segments of the residential market, price is a concern. In the "low
    down up front, high ongoing contractual monthly" market segment,
    perhaps this price can be absorbed, but in the "high up front, low
    monthly, limited or no contract term" market, it must be absorbed up
    front. And two hundred bucks is two hundred bucks !!

  15. So VOIP can travel over the Internet, or over private wiring.
    Regardless whose network it is, VoIP can still cause problems.
    Packet loss, latency and codec issues, as noted earlier, can
    cause a loss of communications with the central station if the
    alarm system is using analog (until recently virtually all were).

    Unless you're willing to spring for a TCP/IP compatible alarm
    system and unless you're working with a central station that
    is equipped to receive alarms over the Internet, you may
    miss signals from time to time.

    One of the problems I've seen using certain ATA devices is
    that they don't like short, quick bursts of DTMF (exactly what
    the alarm system uses when sending CID). Even when I
    dialed rapidly by hand at a rate no faster than 3 or 4 keys
    per second, the devices would miss part of the dialing
    sequence at least half the time. During an alarm call this
    could cause a failure to connect or (worse) erroneous data.

    I have not tried many of the newer ATA devices (only two
    so far this year) but those I have used were still quirky.
    Hopefully, things will improve over the next couple of years
    as more and more businesses change over to VoIP, demanding
    commercial grade services and 100% reliable hardware.


    Robert L Bass

    Bass Home Electronics
    4883 Fallcrest Circle
    Sarasota · Florida · 34233
  16. Carl Carlson

    Carl Carlson Guest

  17. The catch with that, at least in residential, is
    I understand that and you're right to be concerned.
    Unfortunately, this is the way things are going.
    More and more telco's are switching their long
    distance services over to VoIP for the same
    reason homeowners are doing so -- it's less
    expensive. I'm fairly certain that within a very few
    years the major portion of telephony in this country
    will be VoIP. Hopefully, QOS will improve as more
    innovative devices are made.

    Already there are a plethora of direct digital
    telephone instruments on the market, including the
    Polycom 501 SIP unit sitting on my desk. These
    (or something like them) are the wave of the future.
    This doesn't necessarily bode ill for the alarm
    industry -- only for those who fail to keep up with
    the times. [Note: No slight here to my friend, Bob
    Campbell. He's getting ready to retire and move
    to Florida anyway, smart guy that he is... :^)]

    The question alarm company owners need to ask
    is not "How do we keep people from switching to
    VoIP," but "What must we do to be able to continue
    providing services to them?" I believe we're seeing
    the handwriting on the wall concerning phone
    service. I don't pretend to know what the solution
    will be but I'm certain we need to deal with it more
    effectively than by simply warning customers of
    the pitfalls. In case there's anyone left who hasn't
    noticed, they don't always listen. :^)


    Robert L Bass

    Bass Home Electronics
    4883 Fallcrest Circle
    Sarasota · Florida · 34233
  18. Matt Ion

    Matt Ion Guest

    Oh, I would fully expect so. Enterprise phone systems have been using
    VOIP for years, since before the "VOIP" buzzword was coined... often
    only internally, between the desk sets and their switching unit, but
    it's the same basic technology.

    It's like anything else in technology: what you see at the low-cost,
    mass-market consumer level pales in comparison to what's really
    available in features, functions, scalability, and reliability... it's
    only a question of cost.

    Consumer devices will certainly improve as the technology filters
    down... it's only a question of how quickly.
    I don't think we need to worry about VOIP becoming the "de facto" of the
    major providers until that technology IS reliable. The big backbone
    providers (Ma Bell and family) can't afford to dump everyone over to a
    new technology until it's achieved a certain level of reliability... I
    dunno about the US, but up here, if reliability levels aren't
    government-mandated, they're certainly government-encouraged. Telus,
    for example, couldn't just start pulling up landlines and pushing
    everyone onto VOIP if it weren't 99.99% solid - not only would the CRTC
    not allow it, the public outcry would force all levels of government to
  19. Beachcomber

    Beachcomber Guest

    Digital signals sent over a cable network generally use proprietary
    equipment that is provided for and maintained by the cable company all
    the way to the head-end or switching center.

    VOIP is based on the principle of sending packets of data over public
    networks and (hoping) that they eventually get to the right place and
    assemble themselves in the correct order. The Internet companies
    don't care about the integrity of the data packets. They just pass
    them along as routine data.

    Thus, over a period of time, links will go dead, cables will be cut,
    etc. Perhaps redundant circuits will kick in... perhaps not.

    There was a recent news story about fishermen salvaging undersea fibre
    optic cables in Thailand (the cables contain valuable metal conductors
    to power the repeaters). It shut down most of the Internet links to
    that country for weeks. Bad fisherman!

    The big phone companies traditionally have had the incentive to
    maintain their links, and provide redundant links should the main
    circuits go dead. They could afford to give good service because they
    were paid to do so.

    These new breeds of VOIP Telcos just digitize the information and put
    it on the public Internet, sort of like e-mail. It will probably get
    there, eventually, hopefully, but don't ask for a guarantee. And...
    if not... to whom do you call to complain to?
  20. Anders

    Anders Guest

    Even if you normally don't have any issues with your Internet
    connection while surfing the web or emailing, you may run into
    problems using VoIP.

    This is because VoIP needs a constant stream of data to carry
    the audio data. The voice data is chopped into "packets", each
    packet holding maybe 50-100ms worth of audio, and sent on its way.
    If some of those packets get lost, the system tries to "guess"
    what should have been there, and that actually works pretty
    good. The human brain also has a tendency to fill in the gaps so
    most people don't even hear a few lost packets.
    A control panel modem is not as forgiving.

    The latency is also a result of this "packetizing". When a packet
    leaves the VoIP-box, it comes to the router. The router needs to
    receive the WHOLE packet to make sure the checksum is good before
    it sends it on to the cable modem. The cable modem again needs
    to get the whole packet before it moves on to the cable, and
    so it goes for every piece of hardware between you and the
    destination. You can get a feeling for how many "hops" you have
    between yourself and a destination by opening a command prompt
    and typing :
    (or whatever destination).

    Like someone else wrote in this thread, the voice streams
    share the same bandwidth as all other data on the Internet.
    If your YouTube video download halts for a second, you'll not
    notice it because the pre-buffer for several seconds, but 1s gap
    in a voice call is really annoying.

    Some of the cable bundles allocate separate bandwidth for their
    own VoIP, and there have even been rumors about them *limiting*
    the bandwidth or intentionally dropping data when they detect
    competing VoIP packets on their network. Thus it may appear as the
    bundled VoIP works better than for example Vonage.

    So the bottom line is that VoIP is designed for VOICE. Not the
    bleeps and burps a control panel spits out when it communicates.
    A panel designed for networking, bypassing the VoIP modem, will
    work a whole lot better than one using VoIP as a POTS replacement.
    Not to mention the possibilities of having direct remote access
    to the panel and the ability to supervise the connection for

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