sip

If be being written in front
　　
Of many communication respects had been the same as had read me going of age end compose 』 the H.323 agreement inn that how develops oneself with OpenH323 』 , gave very high opinion mostly, can saying even is to be like tide reputably, say to be ashamed, I just had the job of ten people arrange and inducing just, in fact the code of myself has very few one share only (basically be in H.245/H.235 part) , the test version that a lot of friends ask for RTH323 to me later all the time not if really, I explain here, the use as a result of this software and the right that develop 2 times had been bought outright by place of some Europe company, so I had had no right to issue test code, if have inconvenience please everybody is excused.
　　
When we develop RTH323, I had begun to note SIP agreement, and designed many experimental code according to RFC2543, because the development at that time has the translates gateway demand of a H.323-SIP, nevertheless this plan cancelled again later, also began me to have stronger interest to SIP gradually from this moment, just did not do the work with real what, mere and preliminary the whole that understood an agreement is tectonic.
　　
Till last year the end of the year, I contacted the opens former code SIP system of Vovida- – after Vocal, I decide to begin the whole construction of the system that understands SIP, my individual thinks Vocal is a very typical SIP system, center of call of class of all and tectonic telecommunication was included inside, all content of area gateway and relay gateway, and code is clear, transform easily quite; Then I was cost probably the code that the time of 6 months read whole Vocal system, did in a lot of important places tag. As it happens is in this year May, my company has construction the plan of a center of large call of Voice/Video IP business, I refer me to the company to the research achievement of Vocal, plan gets passing,seo, the platform of video phone call that my company is in now and a certain famous university collaboration of domestic prepares to transform level of a company on existing Vocal foundation

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Do not cross my individual and character, to this the plan is not exceedingly satisfactory, because time and pecuniary are restricted, major telecommunications class complement serves the first phase to did not come true, implement this plan only possibly in the 2nd phase, time should last possibly very long, so I also hope to other development companies participate in the development that completes this side very much, we also can seek advice with offerring a technology for the company that have fun at or spread out collaboration of course.
　　
I write the purpose of this article to depend on announcing the positive result of a few research that my individual opens former code system this to Vocal, of course inside it is clear to have a lot of places did not say very much, the design thought that itself should elaborate a program with the character is a very difficult issue, my so many inside scale a lot of chart, will help a reader read the article, what announce this is the content that carries about UA, sequel introduces the Provision Server; Marshal Server; Redirect Server; HeartBeat Server:P in Vocal system in article lieutenant generalOlicy Server:CDR Server:NEtwork Manager:FEature Server: Make an appointment with Ranslator of 脶 of Lv of the 彣 in case children’s hair, the reader needs to have pair of SIP, h.323, MGCP, the basic understanding of QoS, and to Java, XML, call Processing Language, the knowledge of C++ , in the following and paragraphic in won’t basic to these knowledge makes too detailed introduction.
　　
Predicting article publishs the time that ends to need nearly one year probably entirely, 2 development that I hope to software develops a company to finish this article to perhaps pursue Vocal system jointly with my collaboration work.
　　
The commercial application value that from inside the reads Vocal process of this half an year I realize Vocal system is very great, somebody discusses with me on forum: The uses platform difficulty that transforms others and the difficulty that develop an application afresh which bigger, bilateral each buy one word, feel with respect to my individual, if large-scale commercial software undertakes transforming according to open former code, especially platform of a few foundations (for example operating system) , speed is to compare for certain from 0 begin to want a lot of faster, RTH323 is a successful example, this also is the fundamental operation pattern of a lot of software firms of domestic, special to a few personnel, technology, capital is not very abundant company this also may be only program, but the efficiency with the major software of open former code is very low, and code is redundant, annotate is less, readability is very poor, still have a few fatal errors even (Vocal has such mistake in medium Feature Server, often can cause a system to break down) the key that the premise requirement that makes so so can hold to work namely, can discover in time and remove an issue, such ability may transform open former code into efficient commercial application. The net is in charge of net BitsCN_com
　　
Catalog
　　
One. Chock
2. The difference between H.323 and SIP
3. The main content of the article
1. The brief introduction of User Agent
2. UA part is main the introduction of program share
2. 1 main program: \SIP\UA\UA.cxx
2. The 2 substance that found an User Agent
2. Of 3 HeartLessProxy found
2. 4 let User Agent Run rise
2. The implementation of method of 5 HeartLessProxy Run
2. 5. The Run method of 1 WorkerThread
2.5.1.1 ProcessSipEvent
2. 5. 1. 2 ProcessUaDeviceEvent
2.5.1.3 ProcessUaDigitEvent
2. 5. The Run method of 2 SipThread
2. The Run method of 4 in User Agent 6 important example
2. 6. 1 media equipment is started
Cheng of line of the 2.6.2 RTP that start, use at be received to what RTP/RTCP wraps and sending administration;
2. 6. Of list of 3 lawful users get (Redirection Server is special)
2. 6. Cheng of 4 prison line:
2. 6. 5 automatic call
3. Begin a call and await call of the other side:
3. 1 system establishs StateIdle position:
3. 2 begin a call:
3. 2. Part of 1 OpStartCall main program:
3. 2. The 2 incident that obtain clavier
3. 2. 3 condition machine (State) to each operations (Operator) handle a process:
3. 2. All sorts of 4 operations that begin experience of place of a call (Operator)
3. 2. 5 how to enter bide one’s time condition (Idle condition)
3. 2. 6 how to begin to dial and begin a call:
3. 2. 6. 1 OpStartDialTone this locality sends dialling tone;
3. 2. 6. 2 OpAddDigit inputs telephone number to begin to dial:
3. 2. 6. 3 OpStopDialTone;
3. 2. 6. 4 OpInviteUrl builds an INVITE word and send be called;
3.2.7 enter Trying state
3. 2. 7. 1 OpStartTimer starts the timer of every incident:
3. 2. 7. 2 hang machine incident detect mechanism
3. 2. 7. 3 OpStartRingbackTone to be made undertake ring is answered put.
3.2.7.4 OpReDirect undertakes weighing the operation of directional service
3.2.7.5 accredit are checked
3.2.7.6 OpFarEndAnswered handles the OK that receives to respond to
3.2.7.7 how to achieve agreement of RSVP resource obligate in Vocal
3.2.8 users are in communicating StateInCall condition:
3. 2. 8. 1 OpStartAudioDuplex advocate make open RTP channel
3. 2. 8. 2 processing RTP/RTCP wraps:
The processing process OpAck of 3.2.8.3 ACK message
3. 2. 8. 4 OpConfTargetOk is various the conference detects:
3.2.9 call await
3. 2. 9. The detailed description that 1 call awaits:
3. 2. 9. The competition that be in is kept between 2 operations
3. 2. 9. The place in 3 call involves module introduction
The 3.3 call that await the other side
3.3.1 OpRing awaits the ringing news of the other sideChinese net is in charge of allied Www_bitscn_com
3. 3. 2 OpStartRinging begins diabolo
3. 3. 3 OpRingingInvite handles another INVITE information (call awaits)
3. 3. 4 OpAnswerCall is made open media passageway to begin correspondence
3.3.5 return StateInCall condition
4. If where,transform what existing terminal makes to be able to deliver video to flow.
The basic construction of the Codec of a 4.1 H.261+
4. The 2 jobs that add video capability place to need to do
　　
One. Foreword
　　
Be in all sorts of in agreement of communication of IP network multimedia, the SIP of the ought to be ITU H.323 that holds mainstream position in the market currently and IETF two agreements, be in at present market of pure one’s voice in speech, because MGCP agreement has large-scale user enlarge to allow ability application to also presenting ascendant trend, in what the main aspect took on the market before 2000 basically be H.323 agreement, however SIP agreement avoided complex primitive as a result of it (ASN.1) analysis, its application also also got 2000 high-speed gains ground later, have the tendency that exceeds H.323 even, become the competitor with the strongest H.323, of course, a few inherent blemish as a result of SIP agreement (below will introduce these blemish in detail) ,mba, this kind of case won’t appear possibly a few years in future, do not pass the multimedia newsletter business to medium dimensions (receive 60000 hourly) application, use SIP can yet be regarded as one goes to the lavatory, quick development is politic.
　　
Be in all sorts of in the development project that VOIP opens former code, the is based on SIP agreement VoCAL of Vovida (Vovida Open CommunucAtion Library) it is not just be most giant in the inn of agreement of open former code that is based on SIP and perfect, also be perfect likewise in the inn of multimedia communication agreement that opens in all former codes even and comprehensive, the VOCAL1.4.0 that releases at present basically supports RFC2543, according to saying to be in the Vocal1.5.0 of new version will support RFC3261 agreement; Vocal offerred main SIP call control and switch, for example: The user is registered and register, call initialization, modification call is characteristic, or redefine call is characteristic, terminate call; And the basic call of a few users is characteristic: Turn before call for example, call awaits, call block, call move, speech mail is waited a moment.

　　
To the user of system of a Vocal, vocal provided the following a few capability for its likewise:
　　
1. Will deploy whole Vocal system through Web;
2. Canal of use SNMP net will detect the condition of whole system and call group net;
3. The call character list that can define an user (the part of H.450 compensatory agreement in be equivalent to H.323 series) ;
4. Accredit examination;
5. Ad message;
6. The simple QoS that is based on RSVP assures.
　　
In the meantime, VOCAL also offerred detailed documentation and SDK bag to make development in order to give an user 2 times, the user can be in C++ , and Call Processing Language(CPL) , oneself application is developed on Java Telephony API.
　　
2. The difference between H.323 and SIP:
　　
This one content with the article does not have too big concern it seems that, those who do a dependency need to compare between the H.323 that nevertheless the author thinks to regard the market as the mainstream and SIP, lest make,very much reader is immersed in wrong road when choosing an agreement.
　　
Although Vocal can have been a successful example on the application of SIP, so current and pure the multimedia communication system that develops SIP as main body with Vocal from theoretic it is feasible, but in fact at present all VOIP traffic systems are give priority to body with H.323, compatible SIP agreement, return neither one manufacturer it seems that supporting SIP actually (Cisco seems to have similar product, nevertheless applied foreground is not very Anacreontic it seems that) , look above all from the market, the system of H.323 has had much investment, application is very general also, SIP photograph contrast is newer, mature not quite it seems that; Will look from the market, more and more additional services will make applied main trend, SIP domain is opposite for can offer more than H.323, more agile service, and the each other that makes in the letter is epicene on have more much advantage, of course H.323 also can make sure the each other between other solution uses a sex; But, at present MGCP agreement had gotten many industry supports, simple terminal and more complex and perfect call control way let it receive more application, probable meeting becomes the potential competitor of SIP.

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Next we assure to go up from the clause of ITU and IETF in light of, IETFcrm