Emergency Roadside Telephone Network (ERTN)
consists of emergency roadside telephone (ERTs)
installed in pairs along the highway, the ERTs are
connected to a Call Control Unit (CCU) by a dedicated
4-wire (quad) link :
ERT:

	3 available versions :
	Standard, mounted on a concrete slap
	Small body, on a sliding rail
	Main body, for use in a tunnel
	-30° C to +70° C operating temperature range
	1 public switched network line for an ERT
	12 V - 10 Ah battery power supply
	OPTIONS :
	Beacon, Remote control
	Remote monitoring, Solar power

Control center sigtel 3000

Technical characteristics :

Control Center  Terminals :
Capacity :	1000 ERTS
Power supply :	220 V - 50 Hz
Connection :	Up to 3 lines an the public
	telephone exchange
Operating temperature:	+5°C to +40°C
Option :	recording of every
	telephone communication

Communication level :

Standby mode
Call from an ERT
Reply to call
Call release
On-hold feature
Connection with an idle ERT
On-hold call resumed
Last call
ERT defect

Daily record :

Operating daily record
Maintenance daily record