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2. OpenH323

2.1. What is it?

OpenH323 is an open source implementation of the H.323 protocol suite. As such, it can directly interoperate with Microsoft NetMeeting. At the time of this writing (October 2000), OpenH323 is still early in its development cycle; buggy and in flux, but useful.

OpenH323 consists of several C++ libraries and some C++ client programs.

The most useful client programs are:

Table 1. List of client applications

ohphone H.323 interactive client. Linux equivalent to NetMeeting. Supports audio and video; no shared whiteboard, file transfer, or shared applications
openam H.323 answering machine. Plays back a recorded message and records incoming audio. No video support at present.
forwarder Forwards H.323 sessions from one IP address/port to another. Used to serve multiple H.323 destinations from a single IP address.
openmcu Multipoint Control Unit. Connects multiple sessions together into a conference call.
PSTN Gateway Allows NetMeeting clients to make phone calls onto the conventional phone system - the Public Switched Telephone Network (PSTN). Requires special hardware.

OpenH323 presently (October 2000) supports audio codecs G.711, G.723.1, LPC-10, and GSM 06.10, as well as video codec H.261.

2.2. Why is it needed?

OpenH323 is needed only if you want to make audio/video connections with NetMeeting clients directly from your Linux system. It is not needed to provide LDAP directory service to NetMeeting clients.

2.3. Where to get it?

The main site is http://www.openh323.org/ and contains links to a download page, mirror sites, mailing lists, and other resources.

OhPhone, OpenAM, and PSTNgw are available as part of the standard distribution, in both source and executable formats. forwarder and openmcu are presently (December 2000) only available from the CVS archive, as modules named "forwarder" and "openmcu".

2.4. Installation

For OhPhone, OpenAM, and PSTNgw, download the executables. If you want to build from source, perhaps because you need forwarder or openmcu, you'll need the source code to the programs, as well as to the pwlib and openh323 libraries. Compilation instructions are available on the openh323 website.

2.5. Gatekeepers

OpenH323 doesn't provide any gatekeepers itself, but several are under construction based on its libraries. As of the end of 2000, most of them are actively under development and quite primitive. I haven't used any of them myself, but you want may to examine the following links: