Product Name: OpenISDN (H.323 Call Generator)
Product URL: http://www.gae.ucm.es/~openisdngw/home_en.php
Vendor: Open Source
Supported Protocols: H.323
Platform: Any platform where you can compile the OpenH323 Library (Linux, Windows, FreeBSD, Solaris, etc.)
Description:

Operational Experience: It requires ISDN cards to be properly installed and configured on the local machine in order to make connections with the ISDN. It is working only with ISDN lines (no PSTN support)managing n calls simultaneously, so many as ISDN channels available. The Gatekeeper can be in a well-known IP address or it could be discovered in the network with broadcast RAS. Information of the call progress state to the user of the Switched Circuit Network that calls to the Gateway. This information is made with tones similar to the sent by the telephone offices. Support and development has now stopped and it requires special old version of OpenH323 library to compile. No dynamic configuration is possible; once the program is started the client is configured using the command line options. Overall Evaluation: Simple H.323/ISDN Gateway. Needs to be better investigated the complete H.320 compatibility for ISDN conferencing. Right now it seems only an audio gateway.

Product Name: Asterisk Open Source PBX
Product URL: http://www.asterisk.org/
Vendor: Digium
Supported Protocols: SIP, H.323
Platform: N/A
Description:

Asterisk is an Open Source, full featured hybrid TDM and VoIP PBX and IVR platform. It allows you to seamlessly integrate TDM (T1, PRI, FXS, FXO) and VoIP (IAX, SIP, H.323) technologies in a single PBX while providing full IVR functionality through any scripting language available on Linux.

Product Name: Cisco IP/VC 3525 PRI Gateway
Product URL: http://www.cisco.com/univercd/cc/td/doc/product/ipvc/ipvc2_2/2_2prirn.htm
Vendor: Cisco
Supported Protocols: H.323
Platform: N/A
Description:

This H.320 to H.323 Gateway is an older product, identical to the Radvision OnLan Gateway, but OEMed by Cisco and currently not supported any more, as it has been replaced by the 3526 Gateway. The 3525 is capable gatewaying 16 voice channels, or 8 128Kbps participants with H.261 video, or a combination of other rates for multiple BRI bonding. The default hardware does not provide audio/video transcoding, but there existed a hardware add-on for audio transcoding. Check the IP/VC Products page at http://www.cisco.com/univercd/cc/td/doc/product/ipvc/ipvc2_2/2_2mcurn.htm