Internet Telephony Software

There are a number of "Internet telephones" (usually for PCs) using proprietary audio coding and protocols, meant for point-to-point connections. Many of these are migrating to using RTP (mostly as part of H.323 or controlled by SIP).

Articles and Surveys

Another page summarizes news items and references.

Client Software

Company or author Product Notes Windows'95/NT/2000 Windows 3.1 Macintosh Unix
Speak Freely for Unix encryption with DES, IDEA o
Speak Freely for Windows encryption with DES, IDEA o
Digiphone no longer exists
IBM IBM phone for Java 95, NT
Intel Internet Phone H.323 o - - -
Vocaltec Internet Phone o o o
IRIS o o -
SilverSoft SoftFone

RealAudio writes what currently applies to all tools:

If the packet loss is high, it may be due to a busy network. If this is the case, there is little you can do to remedy the situation other than to try connecting to the site at a later time.

Gateways and PBXs

Recently, IP phones are appearing.

Telephony and LANs can also be integrated at the wiring level through IsoEthernet (IEEE 802.9a). Quicknet and others produce sound cards that connect analog phones to computers.

Signaling to set up and control calls is performed by H.323 or SIP.

Last updated by Henning Schulzrinne