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Which is better? H323/SIP?

  • This topic has 3 replies, 1 voice, and was last updated 22 years ago by John Joslin.
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  • #21799
    Revathi Benerji


    Which technology/protocol (H323/SIP)is recommended to provide pc to phone & phone to phone services.

    pls. give your recomended solution for PC to phone.

    thanks in advance…


    H.323 is the most available solution and it works well. However, its capabilities and scalability are limited by the vintage of the design.

    SIP was designed specifically for convergence signaling so it is far better than H.323. Howver, it is a new solution and may not support your environment(desired soluton set)


    Tester please expand on your arguments as I am not sure what you are trying to say. H.323 doesnt scale, because its old. Age also means maturity, which also means they vendors have put in time to scale it fine.

    Also the ITU is finding various ways to get the “protocol” to scale i.e. Annex E. To date the largest VoIP networks are H.323 based. It also has things that SIP doesnt such as mechanisms to keep call state.

    Also im not sure what you mean by convergence signalling? Are you saying that the fact that SIP was created for session management rather than “just multimedia” that it is more flexible for applications other than voice and video. If that is what you are saying then yes, SIP does do that. 🙂

    My point is SIP and h323 are just protocols. No matter what anyone tells you there is no “better” protocols, there are just better ways to do what you need done.

    Since your application is PC to phone apps, it leads me to question a couple of things. Are you building from scratch? If so, it may pay to go the SIP route, that way you can figure out a killer app that can leverage the intelligence of the PC and the flexibility of the SIP protocol. If you want to go with stuff thats already out there… it will depend….do most of your users have the proper client support of a particular protocol.

    IMHO there is no better protocol, but there are protocols that solve some problems better. Define your problem and then weigh the ability of the protocol to be extensible to your applications.

    John Joslin

    Instant messaging for all!!
    A whole country or company or the world on instant messaging.?I look forward to comments on this concept.
    SIP is designed to be used for Presence, Instant messaging and third party call setup. Microsoft AOL etc will convert to a common SIP so I understand.With SIP if your clent stores the number you call direct peer to peer. No setup needed. Most calls will be done this way. The call can be made via E164 telephone numbers, email addresses and IP numbers. It uses ENUM to map email to E.164 tel numbers.
    3G mobile will have SIP in spec. Latest has these I believe. Microsoft. IBM, Sun and all going SIP. Windows XP comes with SIP. SIP being retrofitted to Win 2000.
    In a few years millions of mobiles and millions of PCs, notebooks, smartphones etc will run SIP. It is much more suitable for mobiles I read.
    Envision this. Most mobiles use SIP with list of family members, workteams, club and sports contacts etc. These will be in all the clients mobile and fixed.With SIP and Presence you can see who is online and decide to contact. It is peer to peer. If they are online they answer immediately. If not still peer to peer. But must alert them on client device. Do not have to look up the number. The client Keeps it.
    If all appropriate web pages ( will be XML etc by then) have contact numbers and email and with SIP will be able to see who is online and who needs to be alerted to get response. If you click to dial a call centre you will see who is available !!. Press that call button. Goes direct.Peer to peer.
    In all cases if numbers are not in clients can “dial’ using E164 tel numbers or email address.Then there is third party lookup.
    Having connected in any of these cases you can have a realtime text chat, ot phone call or ( with camera) can have video conference. Will be able to look at whiteboard and soon write notes. If party not there will be able to leave a voicemail or realtime email. Can also do store and forward email of course.
    This all requires IP, VoIP, SIP, SDP, TCP, UDP. QoS with RSVP, DiffserV, and permanent high priority packets.Is not the QoS problem for VoIP solved. Is it now deployment.?
    With instant visibility (ie presence) instant text, voice, video and written notes to anywhere anytime what can be better?. With this linked to voicemail, email, fax, and writing who needs legacy phone networks . This is far superior is it not? Given choice and if economics is right who will go for the “old”.
    In South Africa there are 5million fixed line “old” phones and 12million cellphones. The cell phones are closing the digital divide. In a few more years there will be 20 million cellphones. They could well be mainly 3G with SIP and instant messaging all!!
    We have about 2 million PCs. These could become SIP instant phones overnight!All the notebooks and palmtops and they will also exceed fixed line “old” phones. Furthermore one can expect cheap client server driven SIP fixed phones.
    This is only the beginning. This can be integrated with XML web services.
    With voiceXML the talking internet becomes possible. Not just big banks and big business but everybody will have custom IVR.
    Is this possible. Where are the problems?. What is still outstanding. ? I would love you guys ( includes females) to tell me
    John Joslin
    South Africa

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