What happens if you remove the front of the master socket, but leave the phones as above still plugged in. Can you hear any whistle if the DECT phone is off hook?
PS Google found this.
More and more fascinating - I have just tried your suggestions and this is what happens:-
Wired phone initiate connection first DECT phone on hook - no whistle
DECT phone off hook to join call - no whistle
DECT phone initiate call - wired phone on hook - whistle
Put wired phone off hook - DECT phone still off hook - no whistle
In fact the whistle switches on and off in the DECT phone earpiece as the wired phone is put on hook and off hook repeatedly.
There is no situation where the whistle occurs on he wired phone.
And further test show that with TWO DECT phones attached to the line when one phone is off hook the line whistles - when both DECT phones are off hook whistle stops.
Edited by Shadoogie (Sun 05-Mar-17 08:44:27)