This is the teardown of a Ericsson Aastra MX-ONE telephone exchange. A telephone exchange is responsible for managing incoming and outgoing calls.


The case is a 19 inch rack mount case. The top and bottom are made out of a mesh to let air flow through it.


Case: top and bottom mesh


The case has a backplane for connecting the modules that slide into it to each other. Not every position on the backplane has the same amount and types of connectors. This means that some modules will only fit and work in a specific spot in the case.

Case: Backplane


Unfortunately I do not have much information about the modules shown here. However, they are still worth looking at as they are really well engineered.

DC-DC module

DC to DC unit.

AAU2 module

Access Agent Unit.

ALU2 module

Alarm Interface Unit.

DSU module

Distributed Switch Unit.

ELU33 module

32 Port Digital Extension card.

ELU34 module

32 Port Analog Extension card.

ESU module

Embedded Server Unit.

IPLU module

IP extension unit.

LPU5 module

LIM Processor Unit.

LSU module

LIM Switch Unit.

NIU2 module

Network Interface Unit.

TLU76 module

Trunk Line Unit.

TMU module

Tone Message Unit.