the best place to measure it is on the R&T terminals on the com 2400, as that's where the line is coming in to the panel.
if the com2400 cant see the line it wont dial out, so we need to establish what is happening with the line, the fact you can dial into the unit would suggest a line is there and there is little noise on it otherwise the com2400 will not connect at all.
I have to be honest I don't dial in using the com2400, I use ip these days, its faster for one and I don't have to take a modem and connect to the phone line, just need an internet connection a lot less bother.
Without the answer phone defeat you dial straight into the com2400 from the outside world, with the answer phone defeat you dial in disconnect and then dial straight in, so the line is there, the com 2400 from what your saying doesn't see it outbound and sticks at wait dial tone.
if the com2400 cant see the line it wont dial out, so we need to establish what is happening with the line, the fact you can dial into the unit would suggest a line is there and there is little noise on it otherwise the com2400 will not connect at all.
I have to be honest I don't dial in using the com2400, I use ip these days, its faster for one and I don't have to take a modem and connect to the phone line, just need an internet connection a lot less bother.
Without the answer phone defeat you dial straight into the com2400 from the outside world, with the answer phone defeat you dial in disconnect and then dial straight in, so the line is there, the com 2400 from what your saying doesn't see it outbound and sticks at wait dial tone.