- Provides connection to ISDN exchange for 4 remote subscribers, via multiplexers FM2x2 and FM-MSAN
- Single pair subscriber loop with 2B1Q line code
- PIU-LT (Line Termination) and PIU-NT (Network Termination) options
- PIU unit, as tributary unit within multiplexers FM2x2 and FM-MSAN provides connection of remote customer to ISDN exchange. User NT1 equipment is NT (network termination), whereas U-interface at exchange side is LT. Therefore, PIU unit at customer side must be PIU-LT, and PIU unit at exchange side PIU-NT.
- Remote subscriber can be connected with ISDN exchange via more than one PIU-LT/PIU-NT pair, but maximum number of regenerators is six (i.e. three LT/NT pairs). For test purposes ISDN exchange can send diagnostic commands through EOC channel to each PIU unit in chain. 3 bits are reserved for address. "0" is address of NT1 equipment, "1" to "6" are for PIU units in chain, and "7" is for all stations in chain (broadcast).
Data sheets (pdf): PIU (Serbian), PIU (English)