In a public network environment, products from different companies
must be able operate with each other if Voice over IP to make it
easy to use for end users. To achieve interoperability, standards are being
developed and currently the most common standard for VOIP is the H.323 standard.
- open H323.org - The
OpenH323 project aims to create a full featured, interoperable, Open Source
implementation of the ITU H.323 teleconferencing protocol that can be used
by personal developers and commercial users without charge.
- isdn2h323 -
Project homepage for isdn2h323, a Linux-based ISDN to H.323 gateway.
- NAT H323 under
Linux - Mini-HOWTO for NAT & H.323 - configuring Linux to support H.323
while using network address translation.
- Asterisk - Open Source
telephony switching and private branch exchange (PBX) daemon. Supported
signalling protocols: H.323.
Session Initiation Protocol
- SIP - FAQs, background materials and lists of current work in this field.
- SIP Forum - A membership
based forum. Also contains a news board.
- SIP Center - Portal with
technical and market resources aimed at commercial developers. Also provides
a testbed area for software and proxy development.
SCCP provides connectionless and connection-oriented network
services above MTP Level 3. While MTP Level 3 provides point codes to allow
messages to be addressed to specific signaling points, SCCP provides
subsystem numbers to allow messages to be addressed to specific applications
(called subsystems) at these signaling points. SCCP is used as the transport
layer for TCAP-based services such as freephone (800/888), calling card,
local number portability, wireless roaming, and personal communications
services (PCS). Global Title Translation