| In Administrator (on copier), configure the fax option "Line Parameter Setting", option "Line Monitor Sound" turned to "On" and then back out completely.
Attempt an outgoing fax.
Common issues I have seen are usually shown up by this. You get an operator saying "this number cannot be completed as dialed" or a busy tone kind of sound, are the most common.
Outside line connection (where you dial 9) can be a problem as well, depending on the equipment used on site. In most cases, I recommend the customer insert a pause (P) after the 9, to allow the switchboard time to establish an outside connect before the number is dialed. This is also related to PBX/Outside line dialing in admin mode. Usually I leave this to the operator and do not set this parameter.
Short of those, other issues could be as simple as when the fax was first set up (was the fax parameters initialized when the fax was first installed according to setup instructions?), or basic connection to the line. Dialing method PB vs PBX/10pps. Simply changing this from one to the other and back again can correct some problems. Not obvious I know, but I have had that solve a couple issues.
We have also seen problems like this related to the connection. Is the customer using their own line (long extension)? Is this line a 2 or 4 wire conductor? Our equipment always ships with a two wire conductor, this is important. How was the connection at the wall port setup? Polarity is important, as well as which conductor lines were used there. Is the switchboard connection well?
Are there any splitters in line? I've found these to be totally unreliable even at the best of times.
Most of what I relayed here is what we can do ourselves. Beyond that, it could be switchboard related (usually in house IT), or the telco company needs to be involved for any possible errors on their side. | 
Linear Mode
