NEED THE MACHINE TO ANSWER WHEN THE PHONE SENDS THE SIGNAL.

Receiving a fax
Receiving a fax automatically
1 Make sure the printer is on and is connected to a working phone line.
2 Make sure that Auto Answer is on.
To check if Auto Answer is on:
a From the printer control panel, press (tool icon).
b Press the arrow buttons until Fax Setup appears, and then press ok.
c Press the arrow buttons until Ringing and Answering appears, and then press ok.
d Press again.
Check to see if Auto Answer is set to On.
e If Auto Answer is not set to on, press the arrow buttons until On appears, and then press to save the setting.
3 Set the number of times the telephone rings before the printer automatically receives faxes:
a Press the arrow buttons until Pick-up On appears, and then press ok.
b Press the arrow buttons until the setting that you want appears, and then press to save the setting.
When the number of rings you set is detected, the printer automatically receives the incoming fax.
Receiving a fax manually
1 Make sure the printer is on and is connected to a working telephone line.
2 Make sure that Auto Answer is off.
3 To receive the fax, press (green botton) or press * 9 * on the telephone after you answer it and hear fax tones.
4 Hang up the telephone.
The printer receives the fax.
Receiving a fax with an answering machine
1 Make sure that Auto Answer is on.
2 Make sure you have set the number of times the telephone rings before receiving a fax automatically.
When a telephone ring is detected, the answering machine picks up the call.
• If the printer detects a fax, it receives the fax and disconnects the answering machine.
• If the printer does not detect a fax, the answering machine receives the call.

3 Set the answering machine to answer incoming calls before the printer does.
For example, if you set the answering machine to answer calls after three rings, set the printer to answer calls
after five rings.
Forwarding faxes
Use the fax-forwarding feature if you are going to be away, but still want to receive your faxes. There are three
fax-forwarding values or settings:
• Off—(Default)
• Forward—The printer sends the fax to the designated fax number.
• Print & Forward—The printer prints the fax and then sends it to the designated fax number.
1 Make sure the printer is on and is connected to a working telephone line.
2 Press the arrow buttons until Fax Setup appears, and then press ok.
3 Press the arrow buttons until Ringing and Answering appears, and then press ok.
4 Press the arrow buttons until Fax Forward appears, and then press ok.
5 Press the arrow buttons until Forward or Print & Forward appears, and then press ok.
6 Enter the number to which you want to forward the fax, and then press ok.

You need to go in and adjust the "Off Hook" setting so that it does not pick up the ring cycle before the answer machine does.

Next you have to find the instructions that will allow your phone answer machine to tell your fax machine that there is data for it.

More often than not this is accomplished by setting a software switch for example press number 4 to send me a fax. The answer machine in turns wakes up the fax machine and allow the connection to proceed.

It all in those books that came with your products. I know you keep them neatly filed away for instant retrieval, just the the rest of us do. :)

Don

Go to an electronics store (Radio Shack) and buy a spliter. They sell a spliter that recognizes the call as a fax or phone call and sends signal to proper line. When you hook up the unit you will have your line in, then the outputs will be marked one to the fax and one to your phone. Once you install this your problem will be solved. You only have to hook one at at the fax machine not at all phone jacks.

If your printer has FAX capabilities. Good way to tell is if you have a phone number pad on the front of your printer.

You must have this connected to a phone line for it to receive a fax.
Setup the fax application through your installation CD that came with the Printer/fax machine. Often you set the fax machine to pick up after so many rings. This allows you to leave the printer/fax machine on and gives you time to answer BEFORE the fax machine does. If uncle Bob or Aunt Susie should call to say Hi!

Basically what is happening:
You turn on the Printer/Fax machine it sits idle waiting for a phone call.
Someone now sends you a fax using your phone number.
YOUR printer/fax machine is sitting there listening for the phone to ring.
Lets say you have your printer/fax machine setup to answer after 5 rings.
After 5 rings, your Printer/fax machine will pick up and listen for signal tones from the the other machine. If it gets these, it will "handshake" and send a confirmation fax tone. Then the data will be transferred and printed out on your machine or held in a fax program for you to print or save later.

It is critical that you do not pickup the phone too early or the two fax machines trying to communicate will fail.
If you do this, you will hear an awful squeal and a serious of tones.
You can often hang up quickly and the two machines will transmit again the handshake signals and resume business as usual.

Short answer:
Two fax modems are talking to each other over your phone line to transmit data.

Good luck!
and hope this is helpful.

get a separate telephone cable and attach it to your fax, switch line over from phone to fax manually at the phone line input on the wall, it's the ONLY way I can manage that same problem. If you forget to "switch" your lines over, unplug the fax from the wall & answer your other house phone that's plugged into the wall. Works every time. It takes a little effort, but why pay for more phone lines when all you have to do is plug/unplug an extra phone line?

Problem lies in your Receive Mode setting. If you don't have a dedicated phone line for the fax machine, you need to set it up for either Manual where you answer every call or Fax/Tel whereby the Fax machine determines if the incoming call is a fax or phone call. Instructions per Intellifax 4100 Manual.

Select a Receive Mode
Choose the mode that best suits your needs by pressing the Mode button
repeatedly until the FAX and FAX/TEL lights show the setting you want to use.
Manual
You must answer every call yourself.
The Brother machine must be started manually
to receive faxes.
Fax
For use with a dedicated fax line.
Every call is answered as a fax.
Fax/Tel
For receiving fax and voice calls on one line.
The FAX answers every call and receives a fax or
double rings for you to pick up a voice call.
TAD
For use with an answering device.
The TAD answers every call and stores voice messages.
Fax messages are printed.

If this is on a network your network tech needs to set up your machine through one of the routers.
If the machine was pluged into the phone socet direct, there would be no problem. The phone will ring constantly, until you plug the phone to the machine.
If the machine does not answer the phone, then the problem maybe in the machines confguration for auto answer, or a modem board not working.

But on a network, the computer is trying to find the signal, but can't because it cannot find the machines signal.
This problem is in the network side. Check with your network specialist.

The majority of the time, when you can send but not receive, it is a phone line issue and not the machine. Extremely rare does a machine send and not receive. So here goes the things to try and the reason. 1, Make sure the phone jack is in the "Line" jack and not the external phone jack. Believe it or not, that is the number one issue with sending and not receiving.
Next, plug a phone into the jack that the fax machine is plugged into and see if there is static.
You want to be sure in the fax \settings and advanced settings that the ECM mode is ON, and that Junk Fax ius turned OFF, Junk Fax being on will stop almost all fax from comming in.
Now, the phone line. Here is the explaination of why that can be the problem. When you send a fax, you manually make the connection to the line. When you press send a relay flips and connectes you to the phone line, therefore you have made pretty much a mechanical connection enabling the phone line, and therefore you can send.
Now, when you have an incoming fax, several conditions must me met to make the handshake and therefore connect and receive. These all have to be right in order to properly receive. The phone line voltage mist be high enough, the phone line current must be correct and there can not be much decibel loss over the line. You are making a signal connection, all those conditions must be right to receive a fax. Think of it like a TV remote with batteries that are almost dead, It still send out some signal, but it will not change channels or change the volumn,etc etc. Same principle. If the signal to the incoming fax is weak, chances are it will not connect.

Is your phone line plugged into the proper receptical on the fax? It should be plugged into the LINE slot, not the PHONE slot. The PHONE SLOT IS TO CONNECT A TELEPHONE TO THE FAX. IT IS NOT FOR THE INCOMING PHONE LINE. If your phone connection is correct, try calling your fax machine from a cell phone while you are at the fax machine. Listen on the cell to see if the fax machine picks up the line. If it does not, go into your fax machine's settings, either INITIAL SETUP FAX SETUP, or PHONE SETTINGS. You may have to try several settings to find one that works, depending on your fax machine. Try going to RECEIVE SETUP on your fax machines setup menu. Scroll through the settings, writing each down on paper. Try RING DELAY, RING TIME, NUMBER OF RINGS TO ANSWER , or any other settings relating to how your fax answers the phone line. Try changing each setting, one at a time, and try calling your fax to see if it answers. There may also be settings on your fax to set it up if an answering machine or telephone is on the same line.

Try calling your fax machine from a cell phone. If the fax doesen't answer, or if the line is busy, the phone line may be bad. Also check that the phone line to the fax is plugged into the receptical marked LINE, not PHONE. The PHONE receptical is to connect a telephone to the fax machine. If it still does not answer, try going into the fax menu and go to RECEIVE settngs. Try changing each setting, then call the fax with the cell to see if it answers. Write down each setting before you change it, so you can set it back if changing it does not solve the problem.