Difference between H.323 and SIP

H.323 and SIP are multimedia conferencing protocols supporting phone, video, and data conferencing across packet-switched networks. H.323 and SIP are well-known for their IP signalling standards. H.323 and SIP are standards that define multimedia communication systems and protocols. These protocols may differ in several ways. Essentially, H.323 was developed by the ITU before the introduction of SIP, whereas SIP is an IETF standard.

In this article, you will learn about the difference between H.323 and the SIP protocol. But before discussing the differences, you must know about H.323 and SIP protocol with their advantages and disadvantages.

What is H.323?

H.323 is an application layer protocol that is also utilized for VOIP, and it is a common protocol for audio and video conferences. It is not used for other applications such as application/file-sharing or online games but simply for multimedia conferencing, which makes it simpler than SIP. The International Telecommunication Union (ITU) certified it as a standard for multimedia conferencing over IP in 1996. It is widely utilized by manufacturers of multimedia conferencing equipment and service providers of multimedia conferencing.

It is a binary protocol in which messages are compressed to binary, which makes it appropriate for narrowband connections. The high level of interoperability of H.323 is one of its advantages. It contains some additional capabilities like NAT traversal, support for different addressing schemes, data conferencing, and load balancing. It also features mechanisms that ensure reliability by recognizing issues with network connecting equipment. It is highly compatible with PSTN because the protocol inherits several capabilities from PSTN.

Advantages and Disadvantages of H.323

There are various advantages and disadvantages of H.323. Some main advantages and disadvantages of H.323 are as follows:

Advantages

1. It is a standard protocol.
2. It is stable and mature.
3. It is supported by various VOIP vendors.
4. It provides support for modern VOIP features.

Disadvantages

1. Peer-to-peer architecture requires complicated device configuration.
2. 323 is a suite of protocols (voice, video, and data). It needs additional processing power in terms of processor and memory.

What is SIP?

SIP is an abbreviation for "Session Initiation Protocol". It is an application layer protocol that is utilized for Voice over Internet Protocol (VOIP). It is utilized to control multimedia communication sessions and may be utilized for online games, fax over IP, instant messaging, video conferencing, and even file transfer. SIP was first established in 1996 and is currently standardized by the Internet Engineering Task Force (IETF).

SIP is a text-based protocol that shares features with other well-known text-based protocols such as HTTP and SMTP. It is protocol-independent at the bottom layer, where it supports both UDP and TCP. It can be utilized in conjunction with TLS (Transport Layer Security) to enable encryption.

Advantages and Disadvantages of SIP

There are various advantages and disadvantages of SIP. Some main advantages and disadvantages of SIP are as follows:

Advantages

1. SIP operates independently of the type of session or medium used, providing flexibility.
2. SIP can support numerous users with varying skills.
3. It is an open standard protocol that supports and integrates multiple vendors. SIP uses can be customized via applications.
4. SIP messages are in plain text, which makes troubleshooting easier.

Disadvantages

1. SIP features are continuously being developed, and several vendors have proprietary protocol utilizations.
2. SIP is a relatively new protocol, so fewer people are familiar with it compared with earlier protocols. If you plan to install SIP in your network, make sure you have trained support workers.
3. The text messages processing puts a higher load on gateways. That text should be converted into a language understood by the router and programmed into the Cisco IOS.
4. You should switch between in-band and out-of-band DTMF tones while using SIP and SCCP phones with the same network.

Key Differences between H.323 and SIP Protocol

There are various key differences between H.323 and the SIP protocol. Some main differences between H.323 and SIP protocol are as follows:

1. In addition to multimedia conferencing, SIP may be utilized for file sharing, online gaming, instant messaging, and other multimedia communications. In contrast, H.323 only concentrates on multimedia conferencing.
2. In H.323, the gatekeeper is crucial to call routing and gives routing information. In contrast, the redirect and location servers are utilized specifically for call routing in SIP protocol.
3. 323 shares several characteristics with PSTN (Public Switched Telephone Networks), and it is simple to integrate with PSTN. In contrast, it is not done in the SIP protocol.
4. In the terms of data conferencing, H.323 has full support. In contrast, SIP has limited support.
5. SIP is a text-based protocol that utilizes ASCII encoding for messages. In contrast, the H.323 messages format is in binary form.
6. 323 is more reliable than the SIP protocol and provides tools to deal with a network connection and device failures. In contrast, the SIP protocol lacks such sophisticated failure detection and recovery mechanisms.
7. The H.323 protocol is based on telephony. In contrast, the SIP protocol is internet-based.
8. 323 protocol is a little bit flexible. On the contrary, the SIP protocol is more flexible.
9. In terms of complexity, H.323 is extremely complex. On the contrary, the SIP protocol has moderate complexity.
10. ITU serves as the H.323 standard body. In contrast, the SIP protocol was created by the IETF.

Head-to-head comparison between H.323 and SIP protocol

Here, you will learn the head-to-head comparisons between H.323 and the SIP protocol. The main differences between H.323 and the SIP protocol are as follows:

Conclusion

H.323 is a telephone industry standard that is typically considered heavy-weight, and it accurately defines what is authorized and prohibited by describing the protocol stack. The systematically specified protocols make interoperability easier, but it is complex, an inflexible standard that is difficult to adapt to future apps.

In contrast, SIP is a common Internet protocol that exchanges short lines of ASCII text. It is highly modular, lightweight, simple, and flexible and easily integrates with other internet protocols. However, it does not work with existing telephone system signalling protocols.