v.- 串行异步自动拨号和控制

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1、INTERNATIONALTELECOMMUNICATIONUNIONITU-TV.250TELECOMMUNICATIONSTANDARDIZATIONSECTOROFITU(07/2003)SERIESV:DATACOMMUNICATIONOVERTHETELEPHONENETWORKControlproceduresSerialasynchronousautomaticdiallingandcontrolITUTRecommendationV.250ITU-TV-SERIESRECOMMENDATIONSDATACOMMUNICATIONOVERT

2、HETELEPHONENETWORKGeneralV.1–V.9InterfacesandvoicebandmodemsV.10–V.34WidebandmodemsV.35–V.39ErrorcontrolV.40–V.49TransmissionqualityandmaintenanceV.50–V.59SimultaneoustransmissionofdataandothersignalsV.60–V.99InterworkingwithothernetworksV.100–V.199Interfacelayerspecificationsford

3、atacommunicationV.200–V.249ControlproceduresV.250–V.299ModemsondigitalcircuitsV.300–V.399Forfurtherdetails,pleaserefertothelistofITU-TRecommendations.ITU-TRecommendationV.250SerialasynchronousautomaticdiallingandcontrolSummaryThisversionofITU-TRec.V.250integratesAmendment1(07/2001

4、),Amendment2(03/2002)andAmendment3(07/2003)withthe05/1999versionoftheRecommendation.ThisRecommendationdefinescommandsandresponsesforusebyaDTEtocontrolaV-seriesDCEusingserialdatainterchangeoveranasynchronousinterface.Itcontainsfourelements:–codifiesexistingpracticeincommonGSTN-DCEt

5、hatusetheATtention(AT)commandset;–definesaformatfororderlyextensionoftheATcommandset;–providesasetforstandardizedextensionsforcommonfunctionstoidentifytheDCE,tocontroltheDTE-DCEinterface,andtocontrolDCE-DCEprotocols(signalconversion,errorcontrolanddatacompression);–providesamappin

6、gforthesecommandsintoV.25bisframeformatforusewithDCEsemployingsynchronousserialinterfaces.SourceITUTRecommendationV.250wasapprovedon14 July 2003byITUTStudyGroup 16(20012004)undertheITUTRecommendation A.8procedure.KeywordsAT Commands,datamodems,datatransmission,DCEcontrol.ITUT

7、Rec.V.250(07/2003)97FOREWORDTheInternationalTelecommunicationUnion(ITU)istheUnitedNationsspecializedagencyinthefieldoftelecommunications.TheITUTelecommunicationStandardizationSector(ITU-T)isapermanentorganofITU.ITU-Tisresponsibleforstudyingtechnical,operatingandtariffquestion

8、sandissuingRecommendationsonthemw