Regarding the 2nd line feature, when I tried to change the STUN setting of the secondary line to be the same as that of the primary line, it wouldn't accept the change. The volume level for the two lines is NOT the same, but I haven't tried making any changes there. Finally, there is NO network preference setting for the secondary line, which I assume is intentional.

Any guidance as to which settings on the secondary line should be left alone, made the same as the primary line, treated as totally independent, or what?