Welcome to the The H.323 VOIP Overview Page

H.323 is a specification for transmitting voice, data, and video over the internet. The main characteristic of the VOIP system is that the signal is delivered to both the source and destination over the internet, typically using Cable or DSL Connection. Typically the customer will have to purchase a router to allow more than one internet device in their home that feeds off the broadband connection. This spec includes routing from source to destination, connection, and disconnection of associated digital circuits. Normally copper cable or twisted pair (RJ-11) wire is used at the source & destination, but wireless connections are becoming increasingly popular in large cities.

This system includes VOIP telephones, computing devices, SIP phones, and special purpose devices, and H.323 devices, as well as video, session data transmission, and some security applications that are always connected and some controlled from the internet. Firmware upgrades are often available as technology evolves and industry features and device types are added. Generally speaking this connection is greater than 128 kilobits up and downstream, twice to one hundred times faster than dialup.

H.323 Devices using this technology have been around for a short time compared to POTS or conventional telephone, and are becoming increasingly well known in the mainstream and media as bandwidth improves & becomes more reliable and less expensive, increasingly more stable connections, which are replacing conventional telephones at a rapid rate as broadband becomes more prevalent.

Data rate is bidirectional. Bandwidth is utilized in both directions at the same time, and is shared with other data devices on the same router or network.

  • Operating circuit cost may be monthly or per minute, or free depending on device, rate, plan & configuration.
  • PSTN access is possible on most plans, and may be included in the monthly service price.
  • Good reliability if good ISP, no line noise issues. Network congestion possible.
  • Portable, plug into any LAN line where sufficient is available, anywhere. uses DHCP normally
  • Includes advanced features found in digital telephony
  • Online call tracking, messaging, billing, phone books, etc. May be able to get digital copies of messages
  • E-911 available on commercial services, disadvantage=mandatory fee for it

  • You may be subject the access limitations and policies & fees of your network provider.
  • A monthly cost may accessed whether you use the device or not.
  • 1-2 year Commitments or contracts are the norm, or pay more upfront & self config.
  • May require configuration and some network knowledge or access to use.
  • Your device may only ever work with the provider by whom the device was manufactured or distributed. You're locked in to a single compamy, at their rate. (Vonage, Packet8, Verizon)
  • Startup cost may apply including hardware and connection fee.

    ATA - Analog telephone adapter - allows you to connect an analog telephone to the
    	  internet.  The box you plug your old phone into to use it on the internet.
    	  this is the most general term for such a device.  Converts analog phone signal
    	  to digital format
    DTA - Digital Telephone adapter - Allows you to plug conventional telephone into it.
    	  Used by Packet8, Vonage, Verizon VoiceWing, AT&T CallVantage, etc. 
    	  Service provider may "Lock" the device so it may only be used with their service.
    	  Device is always on.  Broadband & Router required.  Some have router imbedded.
    USB SIP - plugs into USB port on the computer.  Outgoing or incoming calls capable,
    	  depending on plan & options.  When the computer is off, so is your phone, though 
          depending on service may still have voicemail or forewarding.
    IP Phone - Telephone device that is intelligent, programmable, and configured to 
    	  link to a server automatically & includes handset & maybe speaker.  
          Combines DTA & telephone into one device.
    Wifi IP Phone:  Includes wireless 802.11x, DTA & phone into one device.  Accesspoint required.
    	  More expensive device, but replaces 3 devices & uses less wires & takes up less space.
    NOTICE: Information on this page is offered as-gathered, as experienced, and AS IS.
    No guarantees are made, and errors may creep in - 
    Please notify webmaster of any discrepancies you find - thanks!
    Extremely crude configuration diagram of Voip setup:

    Please note that any advertisements at the very top & bottom of the page are from my ISP and beyond my control until I switch domains. It does not indicate my endorsement of such services. Especially Packet 8, who have forgotten what customer service is!

    Created May 11, 2006. Last updated 12 May 2006

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