p1
    OpenVMS usage:channel
    type:         word (unsigned)
    access:       read only
    mechanism:    by value
    The p1 argument contains the channel number of the socket over
    which the TELNET session is to be established.
 p2
    OpenVMS usage:protocol_number
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    The p2 argument contains the protocol selection.
 p3
    OpenVMS usage:characteristics_mask
    type:         longword (unsigned)
    access:       read only
    mechanism:     by value
    The p3 argument specifies a mask of characteristics to apply
    against the connection. See the table in Item List Codes under
    Interface Definition help for possible values.