You will never get a dialtone on an outside line by pressing a call key.What I would suggest is that you assign a DT key for the line(s) on each phone.That way you can have it ring to the one phone and show the ring on the other phones.Be aware that because the other phones do not ring,to answer a call they would need topress the DT key to answer.A DT key will also give them access directly to the line(s) and get them dialtone.Dialling 9 will get them access to an outside line from a trunk group or LCR if enabled