Fax Machine Question

[freemantel]

Just wanted to ask a quick question about fax machines. I bought a fax machine and plugged it into my analogue line supplied by Virgin. I want to be able to fax shops that I am the area manager of.

The problem I am experiencing is that I can fax some of the shops but not all of them. I know all the machines are working as they are used daily. The really strange thing is that they can fax me but I can't fax them. All the lines are BT.

My question is, could it be a phone line issue?

Any help would be appreciated!

 

[Steve]

I want to be able to fax shops that I am the area manager of.

Email is free. Fax is dead.

 

[bernardgreen]

Some telephone lines are not true telephone lines in that they are not a pair of copper wires direct to the telephone exchange.

These non metallic circuits often have restricted band width or create distortion in the sound due variable delays for different audio frequencies and othe non linear effect. This distortion affects speech in varying degree but the human brain compensates for this and the speech is intelligable. But a fax or modem will be confused by the distortion and may not operate properly. Some machines have limited ability to compensate for mild distortion, others don't.

If you line is distorting the fax signal but the line to the shop is not then it might work. If both lines are adding distortion then the total distortion may be too much.

 

[TicklyT]

What happens when a fax call fails? is the call answered, but the machines fail to complete their handshake, or does the call go unanswered?

A few possibilities spring to mind:-

Fax machines designed to detect ringing on pin 3 of the line socket, but pin 3 is not connected / disconnected to cure ADSL problems, so the call is not detected.

Receiving machine set up for manual answer, requiring someone to press the start button on the machine.

Line connected via a telephone system, so incoming fax calls need to be diverted manually to the machine.

Wrong Number - Fax machine plugged into a different line. (Sounds obvious, but it does happen - the ID sent by the machine is programmed manually, and often doesn't get changed if the machine gets moved to a different telephone line).

I have seen an installation where the line pair connected to the fax machine was reversed, which stopped the machine's ringing detector from working.

Another analogue modem connected to the line is intercepting the call. (Some managed ADSL router installations have an analogue modem attached for the management functions).

As Bernard said, The exchange equipment may not recognise the 1800Hz answer tone from the machine, and doesn't provide an appropriate transmission path.

 

[bernardgreen]

From the OP

I know all the machines are working as they are used daily.

Which seems to suggest the installations in the shop are not at fault. So the fault is on the OP's machine or line.

How long does the machine wait for an answer before it gives up on the call and how many rings do the shops take before answering.

TicklyT

The exchange equipment may not recognise the 1800Hz answer tone from the machine, and doesn't provide an appropriate transmission path.

More likely the OP's machine is hearing the answer tone from the shops machine but it has been corrupted so as not to be recognised as a valid answer. As it affects only some shops it might be the duration of the tone sent from those shops is too short. Some cable carried phone services only open the transmit path to the telephone when there is something to transmit. So often part of the first word of a sentence is missing. This effect would also shorten the length of the answer tone and may make it too short to be recognised.

 

[TicklyT]

The 1800Hz tone pulse is an international standard, designed to send the message to the network operators 'I am a Modem', and the network operators should act accordingly. Of course, if the call is travering different networks, there is the problem of whether that information is sucessfully transferred between the operators.

I believe modern transmission methods for analogue modem signals include demodulating the signal from the local loop, just sending the raw data over the public network, then re-modulating it for transmission over the local loop at the distant end. If the network operators aren't working in concert, that just won't work.

None of the problems I listed would necessarily have any effect on outgoing faxes from the shops, but I have encountered all of them preventing successful maturation of incoming modem connections.

OP - Have you tried monitoring the call setup process via a handset or speaker on your machine, or setting up a call manually from your fax?

Hearing someone say 'Hello?' or 'All lines to the Peoples Republic of China are engaged, please try again later', engaged tone or number unobtainable tone (neither tone is always recognised by some machines, especially if their country code is set incorrectly) insead of the expected 'BEEEEEEEP........BLOOP......BZZZZZZ......WOOSHSHSH' could give a clue.....

 

[Faxman01]

Fax machines are designed to "down train" to lower transmission speeds if line conditions are poor...Modern machines run at 14,400 baud, then should automatically downtrain to previous lower speed 9,600 standard if comms are bad.....(line noise etc.) will even downtrain lower as well (7200)
So with your machine...go into "setup options" and set and lock the fax speed to 9,600. Then try sending test fax's to the various shops. If this works ok leave it locked to 9,600. Another idea is to check again in your fax machine "options" if ECM (error correction mode) is switched on/off...if Off try turning On and vice versa.
Another as mentioned earlier try reversing wires connections 2 and 5 in line jack....you may have a earth hum loop problem (Fax PSU and line)...tho' unlikely.
With your outgoing failed fax calls , you can interigate your fax machine for failures ...it will give you the error codes depicting the reason for the ougoing failed fax calls.....line fault etc : )

 

[freemantel]

I want to be able to fax shops that I am the area manager of.

Email is free. Fax is dead.

Totally agree! My company are a bit back dated in that respect!

Thanks for all the answers. I didn't mention what happens when I try to fax. The other fax machine answers and my machine says "connecting". It takes the paper in a little bit but then freezes and doesn't do anything. Eventually I have to unplug it from the mains and plug it back in to get it working again.