Junghanns
Redundancy

ISDN Guard

The Junghanns.NET ISDNguard is an automatic layer 1 failover switch that has been exclusively designed for the Asterisk™ open source PBX. It can be used for various failover scenarios that require a physical reconnection of up to 4 BRI/PRI interfaces.

The Asterisk™ server provides a heartbeat to the ISDNguard over a serial (RS232) interface. If the heartbeat stops the ISDNguard will go into failover state, directly connecting the ISDN NET with the ISDN CPE ports indicated by the red failover LED.
In normal operation the heartbeat stops whenever the Asterisk™ server is stopped. A configuration option allows the heartbeat to continue if the Asterisk™ server was cleanly shut down. Multiple ISDNguards can be cascaded so they can be switched by a single Asterisk™ server with a single RS232 interface.