398 APPENDIX D: CONNEXTIONS H.323 GATEWAY
Overview of H.323 The H.323 standard provides a foundation for audio, video, and data
communications across IP-based networks, including the Internet. By
complying with H.323, multimedia products and applications from
different vendors can interoperate, allowing users to communicate
without concern for compatibility.
An NBX ConneXtions H.323 Gateway provides connections similar to
tie lines between existing NBX systems across an IP network. However, it
can also support voice connections between a 3Com NBX Telephone and
other H.323-compliant devices.
ConneXtions H.323 Gateways support communication with:
■Extensions on other NBX systems that have a ConneXtions gateway.
■Extensions on PBX systems that have an attached H.323 gateway.
■H.323 gatekeepers.
■Miscellaneous H.323-compliant end-point devices such as:
■H.323 telephones.
■Suitably equipped personal computers.
■An emerging class of wireless handsets.
The quality of H.323 calls over the Internet is determined by the quality of
the connection provided by your ISP.
The H.323 protocol addresses these main areas:
■Negotiated Connections
■Negotiated Voice Compression
■Standard Extensions
■Remote Internet Device Connections
Negotiated
Connections
The H.323 protocol adds negotiated call setup and tear-down capabilities
to Internet Protocol (IP) connections. It exists because Internet protocols
were designed to deliver text messages and computer files in data
packets. IP networks were not originally concerned about involving a
person in a real-time conversation as a telephone does.
H.323 provides call setup capability to negotiate the readiness of two
parties to exchange information and how they do it. It then keeps the