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What is CSTA ?

What is CSTA ?. CSTA is a kind of standard communication protocol used between PBX and computer that is famous in Europe. CSTA Protocol. CO Lines. Control Requests. TDA. CTI Server. Event Notifications. Extension Lines. If you want to study about CSTA, please access to the following URL.

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What is CSTA ?

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  1. What is CSTA ? CSTA is a kind of standard communication protocol used between PBX and computer that is famous in Europe. CSTA Protocol CO Lines Control Requests TDA CTI Server Event Notifications Extension Lines

  2. If you want to study about CSTA, please access to the following URL. http://www.ecma-international.org At the top page, select "Publications". Then, select "list" at the section of "ECMA Standards (blue cover) - see index or list". In the list of the documents, "ECMA-269" is the services specification on the CSTA. And "ECMA-285" is the protocol specification. They may help your understanding.

  3. How does it communicate with PBX ? Encoded CSTA message Application KXTDA USB driver PBX USB Encoded CSTA message Windows TCP/IP driver Application PBX TCP/IP

  4. How can you describe CSTA message ? Each message of CSTA is described by using the manner of ASN.1 (Abstract Syntax). It is described by the abstract syntax as following example. Example: Definition about clearConnection message clearConnection OPERATION ::= { ARGUMENT ClearConnectionArgument RESULT ClearConnectionResult ERRORS {universalFailure} CODE local: 5 } ClearConnectionArgument ::= SEQUENCE { connectionToBeCleared ConnectionID, correlatorData CorrelatorData OPTIONAL, userData UserData OPTIONAL, extensions CSTACommonArguments OPTIONAL} ClearConnectionResult ::= CHOICE { extensions CSTACommonArguments, noData NULL} ClearConnection Request ClearConnection Result

  5. How CSTA message is encoded? Each message of CSTA defined by ASN.1 (abstract syntax) is encoded into transfer syntax according to Basic Encoding Rule (BER) which is sent / received between PBX and Computer. < Abstract Syntax> ClearConnectionArgument ::= SEQUENCE { connectionToBeCleared ConnectionID, correlatorData CorrelatorData OPTIONAL, userData UserData OPTIONAL, extensions CSTACommonArguments OPTIONAL} Not supported by TDA Encoding to send Decoding to read < Transfer Syntax> T Tag 30 13 6B 11 30 0F 80 04 30 30 32 44 A1 07 30 05 80 03 31 30 34 L Length SEQUENCE tag V Value ConnectionID This bits stream is represented in HEX.

  6. What is ASN.1 ? If you want the official specification book, please get the ITU-T recommendation book (onerousness). ITU-T X.680 and X.690 is the basic rule about ASN.1 and its coding. ITU-T X.680 Information technology - Abstract Syntax Notation One (ASN.1): Specification of basic notation http://www.itu.int/rec/recommendation.asp?type=folders&lang=e&parent=T-REC-X.680 ITU-T X.690 Information technology - ASN.1 encoding rules Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER) http://www.itu.int/rec/recommendation.asp?type=folders&lang=e&parent=T-REC-X.690 And the following reference book(free download) is also very useful to understand ASN.1. http://www.oss.com/asn1/booksintro.html

  7. Positioning of ASN.1 in OSI 7-Layers Reference Model Defined by ASN.1 CSTA Layer 7 :Application Layer ACSE ROSE Layer 6 :Presentation Layer ASN.1 Layer 5 :Session Layer Layer 4 :Transport Layer LAN USB TCP USB Layer 3 :Network Layer IP Layer 2 :Data Link Layer Ethernet Layer 1 :Physical Layer 10Base-T

  8. How to apply the ASN.1? In general, the description of CSTA message by ASN.1 is not directory understood by the programming tool of Windows. We usually need to use some ASN.1 compiler. The followings are the major commercial compiler. http://www.oss.com/products/products.html ASN.1 compiler takes ASN.1 specification as input, and generates programming language data structures. It also provides encoder / decoder of CSTA messages for the MS-Windows (or other platforms). For example, if you select the ASN.1 compiler for C, the compiler generates (1) C header file that is describing the CSTA message data Structures. (2) C source code file for encoder / decoder (runtime library). By including these files in your application software source codes of C language, you can send and receive the encoded form of CSTA messages by the simple data Structure of C language.

  9. How to use ASN.1 compiler? Your Application (yyyy.h, yyyy.c) Abstract Syntax Definition (XXX.asn) ASN.1 Compiler C language structure (xxx.h, xxx.c) C Compiler C Compiler Object file : xxx.o Object file : yyyy.o Link with ASN.1 runtime library (encoder / decoder) Your application’s executable file ****.exe

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