FAQ

From Email2fax - email to fax gateway for Asterisk

Q1: The script doesn't seem to work.

A: The script contains some special characters (windows end-of-line), so make sure you edit it with an editor that doesn't break it! mcedit from midnight commander is an editor which edit such files properly; most Windows tools will break it.

Q2: The faxes I send are of poor quality.

A1: Make sure your timing in Asterisk is correct (hint: can you receive faxes and do they look OK?).
Run zttest tool (if you have it on your system), get the idea how good or bad your timing is. Generally, it should never drop below 99.98%, and the average should be above 99.99%. The best you can get is 100.00%

A2 Make sure echo cancellation is off when you send the fax. You can set it in zapata.conf:

faxdetect=both

and your Asterisk will try to detect if a transmission is a fax message.

However, it is not always the case, which means asterisk will not always detect it properly. You can check in /var/log/asterisk/full to see if asterisk enables echo or disables *before* it sends a fax - just send a fax from the command line, and watch the logs.

Generally, echo cancellation is a good thing, and you need it for normal conversations, and that's why it will be probably always on (unless you have a separate card for faxes only).

With some hardware you can override it - if you use bristuff (HFC / Cologne-chip, and many more ISDN cards), add m after your channel, for example, if your channel defined in /etc/asterisk/zapata.conf is g0, and therefore, you CHANNEL setting in email2fax is:

CHANNEL="Zap/g0"

to disable echo cancellation, adding m after your channel means:

CHANNEL="Zap/g0m"

Make sure you use the newest bristuff.

A3: Make sure the PCI card you use for faxing doesn't share IRQs with any other cards.

You can verify it with lspci -v and/or cat /proc/pci.

Disable and/or remove all unneeded equipment (like USB, soundcards, serial ports etc. in BIOS). Sometimes you will need to switch your PCI card in another slot, or change its interrupts in BIOS.

Lastly, you can try how your PCI card behaves in another machine - sometimes timing depends very much on a mainboard, chipsets etc.

Q3: I send only 1/3 of the fax or less, why?

A: It seems that Ghostscript versions 7.x can't deal with some PDF files correctly. To check if it's an issue for you, use a --nodelete flag and see the .tiff file created in /tmp/email2fax.

Upgrading to Ghostscript 8.15 (the newest version right now) solves this issue.

You can get it from GPL Ghostscript website, installing is as easy as ./configure, make, make install, and copying ghostscript fonts to the right folder (don't forget to remove your old ghostscript!).

Q4: The last page of my fax is not transmitted although the generated .tif contains all pages, what's the problem?

A: You are probably not using the email2fax-1.2 stable-release. Upgrading to this version should solve your problem.