Hi, on a single extension -- when I select a line -- I hear beeping dial tones for about 16 cycles like the old 'off hook flash', then a constant dial tone for 2 sec and then a sound like 'call not going through error beeping'. (you might have to imagine the sounds....) If I predial on my phone (spa942) and then select the line -- the call goes through. Any idea of what my phone is trying to tell me? thx in advance. Dean.