Introduction To Line Telecommunications

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18. Protocol Buster


This section lists the protocols and standards which may be encountered and gives each a brief description of each. This is not an exhaustive list.







These standards and recommendations are issued by the International Telecommunications Union (ITU-T), formerly the International Telegraph and Telephone Consultative Committee (CCITT), which is a specialist agency of the United Nations.

There are four series of protocol and standard references that are commonly encountered in the area of communications covered by this document. These are

I Series Standards referring to ISDN and related topics
Q Series Standards relevant to European ISDN networks
V Series Recommendations covering data transmission over telephone lines
X Series Recommendations covering the interfacing of data transmission and terminal devices

The following list is for reference.

X Series
Number Areas Covered
X.1 International user classes of service
X.2 International data services and optional facilities
X.3 Packet assembly and disassembly (PAD)
X.4 International alphabet No.5
X.20 Asynchronous communications over PSTN
X.20 bis V series modems - asynchronous communication over PSTN
X.21 Synchronous communications over the PSTN
X.21 bis V series modems - synchronous communication over PSTN
X.22 DTE/DCE multiplex interface for user classes 5 and 6
X.24 DTE/DCE interchange circuits on public data networks (PDNs)
X.25 DTE/DCE packet mode operation across public data networks
X.28 DTE/DCE interface for asynchronous DTE accessing a PAD
X.29 DTE/PAD and PAD/PAD handshake protocol
X.30 ISDN support for X.20 bis, X.21 and X.21 bis devices
X.31 ISDN support for packet mode DTE
X.32 ISDN/PSTN/PDN access using packet mode interfacing DTE/DCE
X.35 PDN packet switched X.25 interface - PSPDN gateway
X.50 International interface between synchronous data networks
X.50 bis 48Kbps for international interface between synchronous data networks
X.51 International interface between synchronous data networks -
10 bit envelope structure
X.51 bis 48Kbps for international interface between synchronous data networks -
10bit envelope
X.58 International interface between synchronous data networks
X.60 Common channel signalling for circuit switched data
X.61 Signalling system No.7
X.70 Terminal & transit signalling of asynchronous services on international circuits
X.71 Decentralised terminal & transit signals on international circuits - sync. networks
X.75 PSS between public networks with data transmission services
X.80 Inter-exchange signals for circuit switched data
X.92 PDN reference model for synchronous connection
X.96 PDN call progress signals
X.110 PDN international routing principles
X.121 PDN international numbering plan
X.130 PDN international connection call set up and clear down times
X.132 PDN international connections - grade of service
X.400 Message handling for electronic data exchange
X.402 X.400 architecture
X.403 X.400 conformance testing
X.407 X.400 service definition conversions
X.408 X.400 encoded information conversion rules
X.411 X.400 message transfer system
X.413 X.400 message storing
X.419 X.400 protocols
X.420 X.400 interpersonal messaging system
X.500 Directory services standard




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Extracted from

Introduction To Line Telecommunications
Copyright Panasonic Business Systems UK Ltd 2000