What is the difference between H.248 and H.323?
These two International Telecommunication Union (ITU)-based protocols are widely associated with VoIP, although both can handle other modes of real-time IP-based communications, such as video. H.248 is the predecessor to H.323, and has its roots in the legacy world. H.248, also known as Megaco, was designed to facilitate the control of media gateways by media gateway controllers. This function was critical in the early days of VoIP, when most of this traffic needed to interface with public switched telephone networks (PSTN) via media gateways.
Ask the expert
Do you have a question for Jon Arnold or any of our other experts? Ask your enterprise-specific questions today! (All questions are treated anonymously.)
While H.248 was initially the dominant signaling protocol for VoIP, it has largely been supplanted by H.323, which was developed from the ground up to support multimedia traffic on IP networks. Since PSTN is still with us, H.248 persists because it supports Signaling System 7 (SS7), the signaling standard for legacy telephony. The future, however, belongs to IP networks, and H.323 is simply better suited to support all forms of IP-based applications, such as voice, fax, conferencing and video.
Not only is H.323 more compatible with SIP, but it supports quality of service (QoS). This is a critical capability that prioritizes real-time traffic, such as voice or video, over other modes in an IP network. When bandwidth resources are constrained, QoS ensures that applications such as VoIP perform properly. Otherwise, quality is degraded and callers experience annoying things like packet loss, echo and jitter.
For more information on H.248 and H.323:
Dig deeper on VoIP QoS and Performance
Related Q&A from Jon Arnold
Is a PBX system required when organizations move to VoIP? Or do they need to replace it? Telephony expert Jon Arnold explains the options available ...continue reading
For employees who work out of the office, are softphone clients or mobile phones the best option? Telephony expert Jon Arnold explains the difference...continue reading
Telephony expert Jon Arnold explains how VoIP and virtual PBX are different, but related.continue reading
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.