The protocols allow many types of features and determine the way in which the VoIP components interact with one another.
Two standards regulate multimedia delivery: ITU ( International Telecommunications Union) and IETF (Internet Engineering Task Force).
Some vendors are using proprietary schemes. Also, not all components of the protocols are used.
Each of the voice protocols has its own advantages and disadvantages and each has a different approach to VoIP.
The most used are:
H323
It is the recommended by ITU.
Its standards were the first used for multimedia delivery over LAN technologies.
H323 Network is based on Media Gateways and Gatekeepers.
They provide call routing an communication with end user devices.
Gateways interface with other Networks like the PSTN.
Gatekeepers function as central servers for call control, admission, bandwidth management and call signaling.
The version two of H323 presents problems for heavier specifications, shortcoming of standards scalability expecially in large-scale deployment.
The following versions solve these problems.
The best use of H323 protocol is in enterprise VoIP applications.
RTP (Real Time Transport Protocol)
The RTP protocol provides features for real-time applications.
Two IP addresses establish the session between two end points.
It is an application built on UDP.
RTCP is not a must for RTP to work, but it helps to provide feedback on the quality of data delivery done by RTP.
Although the feedback does not say where the problems of congestion are, it can be used to locate problems.
It can report where network performance is failing.
It can detect packet loss, delay in transmission, jitter and other problems that can occur.
This information is available on both ends and it is provided by the Media Gateways.
Using RTCP must be used into a small fraction of the section bandwidth.
This should be done not to limit the ability of the transport protocol.
MGCP ( Media Gateway Control Protocol)
It substitutes the traditional voice switches with the Media Gateways.
It is a master-slave control protocol.
The Media Gateway Controller is the “Call Agent” which manages the signaling controls, while the Media Gateway informs the Call Agent of service events.
The Call Agent instructs the Media Gateway to create and stop connections, very often to start an RTP session between two end user devices.
SIP (Session Initiation Protocol)
It is a powerful client-server protocol.
It initiates and stops the calls between speakers which can include multimedia conferences and termination calls.
It is designed to be simple and efficient.
It copies some architectural features of HTTP and SMTP.
It supports user mobility by redirecting requests to the user’s actual location with the aid of a Proxy Servver or a SIP Server.
MEGACO/H.248
It is similar to MGCP.
The Media Gateways provide conversion and sources of calls, while the Media Gateway Controllers control the call.
Its primary focus is the standardization of IP telephony hardware.
It is scalable in implementing a simple minimal design.
The hardware cost is related to the capabilities provided.
Friday, November 03, 2006
Today's new interesting challenge
I have to write a post on PPP forum.
They pay $7,55 and the comment should be "neutral".
That means I can write what I want.
And be paid just to write it.
Well, I think it is not bad, and I do not agree with my Husband (I never agree with husbands)
You're falling so low...
If that is low, well I could even go a little bit lower... I would write it also for $7,50...
Going back to the subject.
I will write what I think a good Forum should be in my opinion.
Providing that the Internet is the Landscape of the mind, and a forum the place where you discuss and exchange ideas, first you have to have a "moderator" which more than moderate, stimulates.
He must be provocative enough and inventive enough to start a conversation.
Always in the background, ready to come in when there is a lack of words.
The world is a dull affair: soundless, scentless, colourless.
It's the brain that does all the work, parses the spectrum, sorts out the shapes and lines, puts all together to form a mental picture.
The words are the expression of the mind and the conversations are the expression of ourselves.
The more the ideas the better the conversation, the more succesful the Forum.
All the rest is just software...
PayPerPost
They pay $7,55 and the comment should be "neutral".
That means I can write what I want.
And be paid just to write it.
Well, I think it is not bad, and I do not agree with my Husband (I never agree with husbands)
You're falling so low...
If that is low, well I could even go a little bit lower... I would write it also for $7,50...
Going back to the subject.
I will write what I think a good Forum should be in my opinion.
Providing that the Internet is the Landscape of the mind, and a forum the place where you discuss and exchange ideas, first you have to have a "moderator" which more than moderate, stimulates.
He must be provocative enough and inventive enough to start a conversation.
Always in the background, ready to come in when there is a lack of words.
The world is a dull affair: soundless, scentless, colourless.
It's the brain that does all the work, parses the spectrum, sorts out the shapes and lines, puts all together to form a mental picture.
The words are the expression of the mind and the conversations are the expression of ourselves.
The more the ideas the better the conversation, the more succesful the Forum.
All the rest is just software...
PayPerPost
Criticism is free: the architecture of trust
Yes, the Internet is nothing else than the mirror of our world.
Virtual reality looks so much like real reality.
It's like Religion, you can smell by far it was made by men.
"The next generation of the internet needs to be able to reassure users that they can establish the original source of the information they digest."
It will never be possible.
If they can hack the information, they can also hack the source of the information.
And I would even suggest that it would be extremely dangerous to reassure users of something nobody can do.
You would create dangerous believes.
It's better to know nothing is certain, nothing can be 100% reliable, so you just take it as it is.
Anyway people believe what they want and like to believe, that is what our society is based on.
To create an effective commercial, a good market product you can promise anything as long as it is feasible...
And then, if you do not fulfill what you promised...it was just a commercial...
I do not think "devotees of blogging sites take too much information on trust", as they do not take too much information on trust from any other mean.
And then:
an idea isn't responsible for the people who believe in it...
Virtual reality looks so much like real reality.
It's like Religion, you can smell by far it was made by men.
"The next generation of the internet needs to be able to reassure users that they can establish the original source of the information they digest."
It will never be possible.
If they can hack the information, they can also hack the source of the information.
And I would even suggest that it would be extremely dangerous to reassure users of something nobody can do.
You would create dangerous believes.
It's better to know nothing is certain, nothing can be 100% reliable, so you just take it as it is.
Anyway people believe what they want and like to believe, that is what our society is based on.
To create an effective commercial, a good market product you can promise anything as long as it is feasible...
And then, if you do not fulfill what you promised...it was just a commercial...
I do not think "devotees of blogging sites take too much information on trust", as they do not take too much information on trust from any other mean.
And then:
an idea isn't responsible for the people who believe in it...
About Pherlure Pherormone
Smell was the first sense. We think because we smelled.
Smell, generated in the primitive brain, is the one sense indelibly printed in the memory.
The fragrance of freshly mown grass conjures up the core of rolling the cricket pitch.
And the smell of a certain perfume can reveal the aromas of a garden,a field of lavender, a walk through cyclamen or the image of the loved one.
...perfume changes our understanding of the conventions by altering our perceptions...
What matters is not what is percieved by the eyes of the observers, but what is perceived in the mind of the observed...
With Pherlure love takes reality by surprise and reveals truths that reality obscures, because the world is mostly in sentations and imaginations, the only reality can be the feeling.
Pherlure Review
Pherlure Articles
Pherlure Relationships
God gave men two ears, but only one nose, so why not using it in the right way?
The perfume has no secret that the provoked conduct does not reveal...
Why not using the right one?
What does smell really express?
It's not about the sensations apprehended from the external world, but about the intimations, intuitions,dreams, fantasies, emotions,the feelings within ourselves..
Smell draws upon feeling and thinking, joining the emotional with the rational.
The only thing you have to do is trying it...
Smell, generated in the primitive brain, is the one sense indelibly printed in the memory.
The fragrance of freshly mown grass conjures up the core of rolling the cricket pitch.
And the smell of a certain perfume can reveal the aromas of a garden,a field of lavender, a walk through cyclamen or the image of the loved one.
...perfume changes our understanding of the conventions by altering our perceptions...
What matters is not what is percieved by the eyes of the observers, but what is perceived in the mind of the observed...
With Pherlure love takes reality by surprise and reveals truths that reality obscures, because the world is mostly in sentations and imaginations, the only reality can be the feeling.
Pherlure Review
Pherlure Articles
Pherlure Relationships
God gave men two ears, but only one nose, so why not using it in the right way?
The perfume has no secret that the provoked conduct does not reveal...
Why not using the right one?
What does smell really express?
It's not about the sensations apprehended from the external world, but about the intimations, intuitions,dreams, fantasies, emotions,the feelings within ourselves..
Smell draws upon feeling and thinking, joining the emotional with the rational.
The only thing you have to do is trying it...
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