IEC TR 62056-41:1998 Data exchange using wide area networks: Public switched telephone network (PSTN) with LINK+ protocol

На французском и английском языках. 77 pages.
Describes a 3 layer data exchange architecture used for communication with large industrial and commercial customer's metering equipment (remote reading for billing purpose). The public switched telephone network (PSTN) is used as a communication medium for this data exchange. This publication is a Technical report type 2.