ZyXEL Communications omni series instruction

∙AT&K00 - (disable V.42bis on ISDN call)

For X.75, to negotiate compression parameters with the remote ISDN terminal, we exchange XID frames before the Link Layer is established. The calling site will send an XID frame with V.42bis request to the called site. If the called site understands this XID's meaning, it will reply to an XID frame with a V.42bis request. If it is able to execute V.42bis; it will ignore the XID or reply to the XID frame with a V.42bis reject or empty information field.

The calling site will assume that the remote site is unable to execute V.42bis if it gets no reply for a period of time after sending the request XID. In this situation, normal connection without data compression will be established.

It takes about 2 seconds for the calling TA to send XID and wait until time out. If you know in advance that the called site has no V.42bis capability, it would be better to issue the AT&K00 command beforehand in order to get a quick connection.

Although not defined in X.75, XID frame is based on the encoding in ISO Standard 8885 and is used in V.42/V.42bis. In addition to the compression parameters, XID can be used to negotiate the packet parameters as window size, packet size ect.

Bundle Connection with V.42bis Data Compression

If both sites have set AT&K44 to enable V.42bis negotiation then XID frames will be exchanged through the main B channel which corresponds to the call established by the first SETUP message.

Only one data compression channel will be used in bundle connections. That means the compression is done before packet disassembly and the decompression is done after packet assembly. The compression ratio of V.42bis is commonly recognized as up to 4:1 for text files. If the line speed is 128K bps, then the DTE speed may reach 512K bps. This makes the DTE's normal RS-232 serial port unsuitable for bundle applications. A special I/O card on the computer side is required in this situation.

X.75 ISDN Communications 69

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ZyXEL Communications omni series user manual Bundle Connection with V.42bis Data Compression

Contents

ZyXEL ZyXEL Limited Warranty FCC Part 15 Information Copyright 1997 by ZyXELAcknowledgments Page ∙ E-mail Contacting ZyXELPage Contents Installing the Windows 95 Driver INF file Understanding AT CommandsOutgoing Calls Incoming Calls Introduction Feature list Configuring Windows 95 Dial-Up Networking Capi InstallationError Correction and Data Compression with Placing outgoing calls Invoking V.42bis Data Compression Answering an X.75 call Making an X.75 CallCall Control for DSS1 Call Control for 1TR6 Old German Isdn Resetting The omni 103 Using The Embedded Protocol Analyzer Diagnostics 100Placing a Call Upgrading with Flash Eprom AT Command Descriptions 109 Viewing and Setting S-Registers 125Register Descriptions 127 Introduction Key Features of the omni Key to Model DifferentiationSpeed and Compatibility Technical Specifications Intelligent Features Physical Characteristics Unpacking Your omniInterface Option How to Become a Registered Owner Introduction Installing omni External Models LED IndicatorsFront Panel Page Back Panel Front Panel Switch Connecting to Your Computer Connecting to the Power Supply Connecting the omni.net to Your Computer Interface Model Connecting to Your Isdn Line Interface Power On and Self Diagnostics Installing omni External Models Selecting the Baud Rate Multiplier Installing omni Internal Models Plug and Play Connecting the TA to your PC Press Y to continue Following message will appear Connecting to Your Isdn Line Interface Model Omni.net Internal Card Installation S/T interface Configuring Your TA Configuring Your Isdn Line and NetworkConfiguring your TA using a Terminal program Type A\setup.exe and press Enter TA should respond Type Page Configuring Your Isdn Line and Network Isdn Communication Basics Understanding AT Commands Supported AT command types Quick Tips when issuing AT commandsType of AT Command Example Command Description Dialing out using Isdn modeOutgoing Calls ATV0 Dialing out for Analog Adapter Port 1 omni.net Internal Dialing out for Analog Adapter Port 1 omni.netDialing out for Analog Adapter Port 2 omni.net AT Command Dial string it will map to Manually switching communication modes non-dataIncoming Calls Placing the Call Determining the Packet Length Digital Data Answering a Call using MSN AT&ZIn=s where ‘s’ is the MSN Command Function Ambiguity resolution switch for voice calls omni.netData over Speech Channel Best-effort call answering non-data Multi auto-answering of data calls Installing the Windows 95 Driver INF file Setup for Windows 95 and NTPage Page Configuring Windows 95 Dial-Up Networking Page Page IPX/SPX Compatible Click on TCP/IP Settings Capi Installation Page Introduction Point-to-Point Protocol PPP Async to Sync Conversion external Feature list Compression Control Protocol CCP Multilink PPP Bandwidth On Demand BOD BACP/BAP Point-to-Point Protocol PPP Answering a V.110 call 110 and Synchronous Mode Communications AT Command Description Making V.110 CallsSynchronous Connections external Command Messages 25bis Command SetCIC DIC DTR Drop-Dialing Operation Indicator Messages AT*D0 56 V.110 and Synchronous Mode Communications Placing outgoing calls 120 Isdn Communications Configuring the V.120 mode Answering incoming calls Dialing in V.120 mode Speeds of 128Kbps Identifying your line provisioningMaking a Bundled Call with Dialing pre-stored phone numbers Error Correction and Data Compression with Selecting V.120 for European Isdn DSS1 Selecting V.120 for Germany National Isdn 1TR6Bundle Connection with V.42bis Data Compression Page 10 X.75 Isdn Communications Making an X.75 Call Answering an X.75 call ATDIphonenumber1+phonenumber2 Invoking V.42bis Data Compression Bundle Connection with V.42bis Data Compression 70 X.75 Isdn Communications Handling Analog Calls non-data AT&V6AT&V7 Placing a Call from the Analog Adapter European switch specific Scenarios of an Incoming Voice Call Outcome Accepting an Incoming Call AT Commands Description Commands Description Feature Phone omni.netFlash key InterCom Call Waiting Placing a second callReceiving a second call Call Reject Call BrokerCall Transfer Three-way Conference Call HFlash è H#3 Control of Outgoing Service Indicator Advanced Isdn Call ControlCall Control for DSS1 S108+n= Function S80 bit ‘n’ as followsS108.n= Function = YnNnown-number/Znown-Subaddress Control of Isdn Phone Number and Sub-address Call Control for 1TR6 Old German Isdn Control of Endgerä Teauswahlziffer EAZ ModemG3 Fax Command Function Answering a Call for DSS1 Answering a Call Best-effort Call Answering Answering a Call for 1TR6 Ambiguity Resolution Switch for Voice Calls non-data Multi-Auto-Answering of Data CallsData Call Indication Disable inbound call connection Placing a Call Point-to-Point ConfigurationPlacing a call for DSS1 ATDxYnNncalledpartynumber/Zncalled-party- subaddress Placing a call for 1TR6 Leased Line Isdn ATDB2 ATDB1ATDB3 ATAB1 Security Types and Levels Security Functions Level 2 security Level 1 securityLevel 3 security Level Setting and Modifying Passwords Non-password Auto Call Back Function Security Functions Upgrading with Flash Eprom Upgrading Your omni Kernel Mode Diagnostics DiagnosticsTest Test Description Power-on Self-test Isdn Loopback test AT&T9Loopback with Self-test AT&T10 B1/B2 Loopback with Self-test AT&T11 Diagnostic Command Atcg Using The Embedded Protocol Analyzer Resetting The omni Capturing the Protocol Data CD1 CD0CB0 CB1 Key Function Description ATC$ Diagnostics Simplex mode AT Command Set ReferenceMultiplex mode Operation Modes of the DTE Interface Basic AT Command Set AT Command Descriptions All the Following Commands Require a AT Prefix Command Options Function & Description BP0 BP1CE0 CH? CE1CL? CP0 Command Options Function & Description DB2 DB1DB3 DN? USA ATI SPID0 IsdnSPID1 SPID? Description of ATI3 Output UPXOutput Parameter Output Value Description Extended AT& Command Set Isdn Command Options Function & Description Command Options Function & Description Extended AT* Command Set Command Options Function & Description AT Command Set Reference Viewing and Setting S-Registers Status Registers and Result CodesViewing S-registers Setting S-registers Bit Binary value Decimal value Hexadecimal value Register DescriptionsOperation Example-1 Example-2 Binary Dec Hex Not Command Bit Dec Hex Function and description Command Function & DescriptionBasic S-Registers ATSn=x Extended S-Registers ATSn=x Command Bit Dec Hex Function and description ATX0 ATX1ATX2 ATX3 ATX4 Command Bit Dec Hex Function and description Command Bit Dec Hex Function and description Command Bit Dec Hex Function and description Complete Command Bit Dec Hex Function and description Enable loopback 4 test DCA function enabled Command Bit Dec Hex Function and description SI= Fernsprechen analog 48000 bps PPP/MLPPP Command Bit Dec Hex Function and description PPP ATV0 ATV1 ATXn Result Code Option Table Connect Result Code Chart Symbol Reference Result Code Field DescriptionsField Name Possible Values Connect Strings for Error Corrected Connections Status Registers and Result Codes Phone Jack Pinout Assignments Not Connected Phone Jack Pinout Assignments Serial Port Interface Signal/Pin Number Description Direction NamePin DCE MAC DTETXD RXD RTS CTS DSR CD DCD DTR Index Index Bundled Index