Tele Menu - all about Voice Over IP


Let's first consider how VOIP can be deployed without any links to the phone network. In this setup, parties connect using sound capabilities of their Internet-connected computers, but they won't be able to place or receive telephone calls (telephone as in "1-212-999-9999"). Sometimes, such variants of VoIP deployment are called "IP-to-IP".


The main requirements for the IP-to-IP setup are:
  • Computer with a sound card
  • Broadband Internet connection
  • Communications software


The main advantage of IP-to-IP is cost, or the lack of it. Save for the cost of your computer setup and Internet connection, there is no cost to making voice calls. In other words, the connections are virtually FREE.

Disadvantages exist, too:
  1. IP-to-IP does not integrate with the analog phone system. In most cases you can not make calls to phone number or receive calls to a phone number.
  2. Establishing the connection requires your party to be using the same protocol.
  3. IP-to-IP is often difficult to configure, especially if there are issues with NAT ( 1 ).


The following describes popular VoIP software options at the end of 2003. Note that some products, such as GnomeMeeting for Linux, utilize standard VoIP protocols (H.323 and SIP), and some, such as Skype implement their own protocols. A connection between two parties is established either by one party "calling" the other directly via their IP address or by using a public directory.
  • MSN Messenger (Windows) as well as other "messenger" clients (AIM, Yahoo, ICQ)1. A lot of devepment is happening in this area, but at present, the applications have numerous issues ranging from NAT incompatibility 1 to confusing interface. Microsoft is moving toward integrating voice features into its Office suite. AIM is presently utilizing Net2Phone as the "voice" plug-in. Stay tuned - it's all but inevitable that voice features of major IM clients will be upgraded in 2004.

  • GnomeMeeting (Linux) 1 - one of the most popular programs for Linux users utilizes the H.323 protocol and allows to easily add video. GnomeMeeting is cross-compatible with NetMeeting.

  • Skype (Windows). Skype is based on the p2p architecture used in KaZaa and has managed to avoid most NAT-related problems 1, but at a cost: the protocol used by this application is non-standard (it's neither H.323 nor SIP). As of the time of this writing (December 2003) Skype is the only major VoIP player utilizing P2P.

    Skype is currently free, but says the following about its future plans:
    What does it cost?
    During the beta period Skype is free and helps us to refine and improve our product. Eventually, some features and services of Skype will require a paid subscription or prepayment. Our ambition is to keep the basic functionality of Skype (PC to PC calls) free. More information will be provided once our beta program is complete.
  • NetMeeting 1 (Windows) [NOTE: the program being phased out by Microsoft] - still relatively widespread program utilizing the H.323 standard.
These software packages are either free or bundled with other products and they generally allow users to connect to each other bypassing the phone network

(There are also software packages that allow you to dial regular phone numbers from your PC. They, however, require you to subscribe to a service, which is not free. The most popular piece of software is Net2Phone which is integrated with some of the most popular messengers. This is discussed in more detail here).



1 These programs share the same drawback which is that if they are used from behind firewalls using NAT(Network Address Translation), the firewall needs to be configured in order to allow for VoIP traffic to "pass through". More information on firewall configuraions is available here.
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