That's a good solution Flemming!
Mike also returned to my other question, saying that the radio (blackbox) RRC switches off the radio after about 1 minute SIP loss.
The radio I use now (706) eats virtually no current in standby, so it goes to sleep when my control panel RRC is timed out by a simple sleeptimer.
You're solution is even better, CO2-wise :-)
73
Paul
PD0PSB