I am facing issue on siemen exchange that one of the Slmo24 Q2168 x all phones have no dial tone.on display phone it seems like disay goes on/momentary. It seems that Q2168 is not giving output . There us no fault on Q2168 but phone don't have dual tone. Tried to replace Q2168 card but didn't nske difference. Is Q2168X is plug and play or it would have any procedure. Please give us your thought