We have a HP colour laser jet CM2320nf MFP and when we try and send a fax it comes up with error report Comm Error 345. Please explain

Check phone line. use a normal phone and plug into the same phone wall socket that the MFP is using, do we have a dial tone? Do we have a noisy line, any buzz or crackel will cause issues

If there is no dial tone ring line supplier, If it is noisy line do the same

Also check phone line is plug into "line" socket in the back of machine not "ext'

Also check no prefix is required to dial out, unit needs its own phone line..

Also try using resolution of fax as standard not fine, this requires less info to go threw the line

In Australia we have a thing called folds (fax online diag service), basicly it is a fax number you ring and the phone company who own the line send back a report, most times the issue is noisy line or no line available

hope this helps

Cheers
Soulvisitor