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  • Embedded H.323 Protocol Stack
  • Pre-Ported H.323 Protocol Stack

H.323 Protocol Stack -- Source Code


elemedia® H.323 Protocol Stack

The Agora Labs software platforms are the most scaleable and reliable in the industry. Originally sold by Lucent’s elemedia venture, the stack has been thoroughly tested and utilized by IP service providers. Today, our products are among a minority of offerings usable in both high-end networks, small endpoints and on PCs and workstations..

The Agora Labs elemedia H.323 Protocol Stack product line implements the ITU family of H.323 protocols and makes them available to you through flexible, highly reliable software. This H.323 SDK is recognized industry-wide as being memory space and time efficient, and highly interoperable—a trait necessary for carrier-grade solutions. 

The Software Architecture    

Modular and hardware-independent, Agora Labs’ software architecture is a perfect solution for carriers with heterogeneous configurations.

The Agora Labs Advantage

With all of the other IP Telephony platform providers in the marketplace, why choose elemedia? We offer a competitive advantage over the other providers in the following areas:

  Modular and flexible design enabling cost effective, distributed, and scalable implementations

  • Carrier-grade quality: high reliability, high scalability, and high interoperability
  • Scalability from low-end to carrier-grade solutions for central office applications
  • Flexible design enabling distributed architectures
  • Expertise and assets in Internet telephony software components:
    • H.323 Protocol Stack
    • Video codecs
    • Audio and Speech codecs

EX3230S Embedded H.323 Protocol Stack

Agora Labs’ Embedded Protocol Stack is specifically architected for embedded processor systems that typically rely on lightweight operating systems and require minimal footprint, modularity and integration flexibility. Its low-level API allows you to customize and tune the Stack to meet your application needs. It is written in the "C" programming language, and makes minimal use of operating system functions, so it is highly portable and suitable for a variety of platforms, from a VoIP phone to the largest servers. 

The H.323 source code library was designed for high-performance, high-density embedded systems, and is also available ported to Windows, Linux and Solaris.  Softswitches and large gateways can take advantage of the low memory space requirements and fast execution speed of the stack.


The Agora Labs EX3230S Embedded H.323 Protocol Stack fully implements the ITU H.323 V1.0, through V5.0 family of protocols;  additional features have been implemented as users have requested them. 

Some of the features of the H.323 SDK are:

  • Platform and OS independence
  • Suitability for embedded processors, workstations, servers and high-availability platforms
  • Event driven-state machine implementation without dependence on threads
  • Dynamic memory allocation not mandatory
  • Real-time support
  • Transport independent
  • OS and processor independent
  • easily ported to other OSes

PX3230S Classic H.323 Protocol Stack

Designed for the PC and workstation, hosted processor market, the PX3230S H.323 Protocol Stack implements the ITU H.323 family of protocols in a flexible and easy-to-use software package.

 The PX3230S protocol Software Development Kit software helps to simplify the development of complex communications applications. ThH.323 software library contains the EX3230S stack as its core and adds a high-level C++ Application Programming Interface. The combination of this small footprint, low-level core and easy-to-use high-level API provides developers with an H.323 Protocol Stack that supports development of a wide range of products. The comprehensive API documentation is provided in HTML format, which allows it to be always available on-line—regardless of the platform chosen for development.

RTP Protocol Stack

Agora Labs also supplies an RTP stack, written in “C” that has been architected for scalability and high performance.  This RTP stack include the RTCP protocol and supports the use of the Agora Video Codecs.

Our Stacks’ Heritage  

The elemedia H.323 protocol stack was, and is, recognized as the leading H.323 stack. While developing the elemedia products, Lucent engineers and scientists chaired many ITU committees, including the ones responsible for the H.323 specification.  

Agora Lab’s Pledge to Evolve

The H.323 standard is evolving and Agora Labs pledges that its H.323 Protocol Stack not only keeps pace with the evolving H.323 market but leads in technology and innovation—guaranteed.

About the H.323 protocol:

H.323 is the protocol that is most commonly used for videoconferencing and for voice over IP (VoIP).  H.323 and SIP are currently the two most commonly used VoIP protocols.  H.323 offers greater compatibility than SIP because most of the VoIP equipment in the field supports the H.323 protocol.  H.323 also offers greater interoperability than SIP because the ITU used ASN.1 to define many of the protocols that make up the H.323 signaling protocol.  Signaling protocol stacks described by ASN.1 are difficult to implement, but result in products that are very interoperable because ASN.1 thoroughly describes the protocol and doesn't leave room for (mis)interpretation.  If you are developing VoIP equipment that needs to interoperate with equipment from other manufacturers, the H.323 protocol will give you better interoperability than other VoIP protocols.  And Agora Labs has developed an H.323 signaling stack that makes it easy for you to implement the H.323 protocol.