I have a Panasonic KX-FHD331 fax machine.  People have not been able to fax in and I want to make sure everything is hooked up RIGHT.  I have the phone, fax machine, answering machine, caller id box.  There is something I am doing wrong here and just don't know what it is.  Explain this like you would to a little kid if you will.  Thanks.  I have ONE line.Hello, please make sure the phone line is CONNECTED well. You can try to print out a report and see whether there is some bad codes.The phone is connected right;however, the manual doesn't show or tell how to CONNECT the fax, the caller id, and the answering machine.  I have re routed a few things and just need to see if an oncoming fax will come in.I haven't used a fax/modem/phone switch for years, so I can't recommend a specific brand or model, but I have used them in the past.  It may be something you might LOOK at.

One example.

http://www.amazon.com/ComSwitch-Telephone-Sharing-System-Switch/dp/B0000YE3Q8

An incoming fax has a specific ID that the switch uses to route the call to the fax machine instead of the phone.

Does your phone or fax machine not have caller ID?  Do you really need a separate caller ID box?