ISDN-oriented Modular Interface

IOM is a system architecture and its bus for communication between various VLSI ICs for the lower layers of ISDN. It was developed by Siemens (today: Infineon), current revision is IOM-2. Its purpose is to enable modularity. Second sources are AMD, Alcatel, Plessey.

IOM-2 is a 4-wire serial, full-duplex link. 2 operation modes are available: line card mode and terminal mode; which differ only in number and purpose of the channels. Signals are:

• DCL (data clock, 16kHz * N, where N = number of channels)
• FSC (frame sync, 8kHz)
• DU (data upstream)
• DD (data downstream)

• ((Cite book| year=1991 | title=ICs for Communications, IOM–2 Internal Reference Guide | publisher=Siemens AG))
• ((Cite book| year=1994 | title=ICs for Communications, ISDN Subscriber Access Controller for Terminals, ISAC–STE,

PSB2186 User’s Manual | publisher=Siemens AG))

• Georg, Otfried (2000). Telekommunikationstechnik. Springer. ISBN 3540668454, 9783540668459. {{cite book}}: Check |isbn= value: invalid character (help) (in German, p. 278ff give an overview and some application examples)