Re: [fw-wiz] VOIP versus PBX

From: Patrick M. Hausen (
Date: 07/21/05

  • Next message: Aaron Smith: "Re: [fw-wiz] Forwarding traffic to an active IDS/Firewall"
    To: Scott Stursa <>
    Date: Thu, 21 Jul 2005 23:00:37 +0200 (CEST)

    Hello, Wizards!

    Scott L. Stursa wrote:

    > > I was also concerned that the VOIP system would mean every call - even
    > > desk-to-desk would go through the internet
    > Probably true if the VOIP PBX is not on your premises.

    > [...]

    > So I don't feel I'm risking much, by stating in this public forum:
    > Don't do it. Stick with a traditional (non-VOIP) PBX.

    With the recent second hype about VoIP I'm always a bit puzzled
    why people imply that you have to get "VoIP service" if you
    want an IP based PBX.

    I'd take an IP based system any time, but:

    - rent a conventional phone service -> no problem with 911
    - buy, not rent an IP based PBX and end systems (aka "Phones" ;-)
    - run VoIP on my strictly internal network

    I like VoIP, I agree with Marcus that it's loaden with
    probable security risks but if you know about them, you simply
    don't connect it to any public network.

    So, if you act like I would, what does VoIP buy you in the end?

    At least in Germany PBX systems are the most "locked in" pieces
    of IT that I've ever come across. Ridiculous licensing models,
    no documentation, vendors force you to rent their service
    for simple configuration tasks or charge ridiculous amounts
    for their propriatary configuration software.

    If you happen to actually buy instead of rent a PBX by a company
    that does provide documentation (like Ascom, Switzerland, for example)
    the configuration concepts of a PBX are rather weird to networking
    people (IMHO).

    We sell the products of a German company named Innovaphone. They
    produce fine (again, IMHO) IP based PBX systems - they are much
    more similar to the configuration philosophies we are acustomed
    to - routing based on longest prefix match, for example.

    You simply buy the stuff, it comes with full docs, you set it
    up. Period. No extra fees.

    Their IP based phones can fetch the central phone book from an LDAP

    The phone registers itself at the PBX with its MAC address.
    Unplug phone, go to next office, replug - you just moved
    including maintaining yor phone number ...

    I simply appreciate the similar concepts, the flexibilty in
    configuration an the fact that it's completely under my
    control. We've been using this stuff since 1998, so the vendor's
    been around at least for a while. We have Country and Western
    - we have a conventional PBX and the Innovaphone Equipment
    connected to it. If I'd buy completely new, I'd go completely

    And in case of a power failure - our conventional PBX doesn't
    have an emergency power supply. I have a cellphone.
    And power failures in Germany are typically in the seconds range
    and occur _very_ rarely.
    I've had more downtime due to UPS's breaking than due to real
    power outages.


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