1．service class indication, +fclass?

    the current service class setting of a facsimile dce is interrogated by the "+fclass?" command. the information text response is a single value:

    0 indicates a data modem

    1 indicates a service class 1 facsimile dce

    2 indicates a service class 2 facsimile dce

    other values are reserved

    2．service class capabilities, +fclass=?

    the service classes available from a facsimile dce are probed by the "fclass=?" command. the information text response is a list of values, separated by commas. for example, a dce that supported data communication and facsimile service class 1 would respond: "0,1 ".

    3．service class selection, +fclass=[value]

    the service class may be set by the dte from the choices available (see above), using the "+fclass=[value]" command. to configure a dce for service class 1, the dte issues the command: "at+fclass= 1".