What is CSTA CSTA is a kind of

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. 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.

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

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 clear. Connection message clear. Connection OPERATION : : = { ARGUMENT Clear. Connection. Argument RESULT Clear. Connection. Result ERRORS {universal. Failure}Clear. Connection Request CODE local: 5 } Clear. Connection. Argument : : = SEQUENCE { connection. To. Be. Cleared Connection. ID, correlator. Data Correlator. Data OPTIONAL, user. Data User. Data OPTIONAL, extensions CSTACommon. Arguments Clear. Connection Result. OPTIONAL} Clear. Connection. Result : : = CHOICE { extensions CSTACommon. Arguments, no. Data NULL}

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> Clear. Connection. Argument : : = SEQUENCE { connection. To. Be. Cleared Connection. ID, correlator. Data Correlator. Data OPTIONAL, user. Data User. Data OPTIONAL, extensions CSTACommon. Arguments OPTIONAL} Encoding to send Not supported by TDA Decoding to read < Transfer Syntax> 30 13 6 B 11 30 0 F 80 04 30 30 32 44 A 1 07 30 05 80 03 31 30 34 T Tag L Length SEQUENCE tag Connection. ID This bits stream is represented in HEX. V Value

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/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/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/asn 1/booksintro. html

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

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. 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.

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 Object file : xxx. o Object file : yyyy. o Link with ASN. 1 runtime library (encoder / decoder) Your application’s executable file ****. exe