BusinessPhone Communication Platform 5.1
System Description ASB 150 02 > Hardware

## Add-on equipment

#### Thermometer

Up to three external temperature sensors, RPM 603 339/1, can be connected to CPU-D_ and the AUX_-board. Only one reading is displayed on the telephone set.

#### Excess voltage protection

The boards of the PBX are furnished with "secondary" excess voltage protection on the line inputs. For more difficult external conditions a primary excess voltage protection should be mounted. Refer to the “Installation Instructions” for suitable precautions. Main distribution frame SXK 106 4139/1 has room for this primary protection.

Revision: M © Ericsson Enterprise 2003