Using the added features

Contents:

Options specific to TDM400P and clones

DKMS Support (DEPRECATED)

The big advantage of using DKMS is that the kernel modules will be automatically rebuilt whenever a new kernel is installed.

Unfortunately, DKMS is horribly broken on Red Hat-based systems. Here's what happens:

Install a DKMS-enabled module.

Update your kernel a few times.

Watch in horror as the module(s) fail to load, because the old kernel they were compiled against gets deleted.

Spend lots of time cleaning up the mess.

Basically, the problem is that Red Hat-based systems try to save you some time by making symlinks to your original modules, pointing at the first kernel on which they were installed. When that kernel gets deleted, the symlinks end up pointing nowhere.

Because of this, I don't recommend DKMS unless you're using a Debian-based system.

You will need to install DKMS on your system. If you are using CentOS and the repoforge (formerly rpmforge) repo, you can install it with yum. Ubuntu has a package that can be installed with apt-get.

Example (assuming 2.4.1.2 drivers and 2.4.1 tools):

Ignore Flash Forward

A phone attached to a DAHDI (or legacy Zaptel) FXS channel that is not configured for three-way calling can send a flash forward signal, which can be propagated via IAX to an FXO port on a remote Asterisk system. This can allow the caller to drop to a dial tone on the remote FXO port. If this is undesirable to you, it is possible to configure your FXOs to ignore flash forward.

Settings for /etc/dahdi/system.conf:

Dial Pulse Mapping

Oslo, Norway, New Zealand, and Sweden used different arrangements for rotary dials than the rest of the world.

World:	1-2-3-4-5-6-7-8-9-0
Sweden:	0-1-2-3-4-5-6-7-8-9
New Zealand, Oslo	9-8-7-6-5-4-3-2-1-0

Let's say you have New Zealand-spec UAX13 switch hooked to FXO ports 1 and 2 for incoming traffic, FXS ports 3 and 4 for outgoing access, a rotary dial phone intended for Sweden on port 5, and an Oslo or New Zealand rotary dial phone on port 8.

Settings for /etc/dahdi/system.conf:

Additional Tone Zones and Secondary Dial Tones

Additional tone zones are available, which also provide distinctively different secondary dial tones when you use the ignorepat option in /etc/asterisk/extensions.conf. Use the names below with loadzone= and defaultzone= settings in /etc/dahdi/system.conf, and the numbers below with the tonezone= parameter in /etc/asterisk/chan_dahdi.conf. The following tone zones are available:

system.conf name	chan_dahdi.conf number	Description
xm	100	Tones used in the 1960 Bell Labs experimental ESS trial in Morris, Illinois. Also provides a 350+440 Hz secondary dial tone.
xp	101	North American tones with 500+640 primary and 350+440 secondary dial tones.
xu	102	Old style UK tones, with "purring" primary dial tone and 350+440 secondary.
x1	103	Standard US tones with 500+640 secondary dial tone.

Configurable Digit Timeouts

The digit timeouts for chan_dahdi can now be configured from the chan_dahdi.conf file. Note that they affect all DAHDI channels. Values are in milliseconds.

Settings for /etc/asterisk/chan_dahdi.conf:

Dial Speed Testing

Support for dial speed testing is built-in; no options need to be set. You may either use the dial speed AGI application, or roll your own using the hookswitch logs. Each DAHDI channel will have a log that holds the pulse count for the last pulse digit dialed, plus the last 20 hook state transitions (corresponding to ten pulses). These will be found in the /proc/dahdi_dial directory. For example, /proc/dahdi_dial/3 holds the hook state log for channel 3. Here's an example log, immediately after dialing a 0 into the dial speed test AGI:

A value of 0 for the zt_hooksig indicates a "break" (on-hook) condition, while a value of 1 indicates a "make" (off-hook) state. The numbers that follow are a standard UNIX-style timestamp (seconds past the epoch), followed by the number of microseconds. Strictly speaking, a decimal point could have been put there instead of a colon.

Dial Pulse Debounce Setting (TDM400P and clones)

The wctdm driver has a dialdebounce option specified in milliseconds. In the official Digium version, this defaults to 64 ms, but that doesn't work very well for real pulse-dialing phones. The C*NET version defaults to 32, and works better. However, if you still have problems using rotary-dial phones, you can change this in /etc/modprobe.d/dahdi or /etc/modprobe.conf file. The value must be a multiple of 4. It is not necessary to set fxshonormode when using this option.

Example:

FXS ring frequency selection (TDM400P and clones)

If you have a US-spec phone with a frequency-selective ringer, you can configure the TDM400P to supply ring current at different frequencies than 20 Hz by using the opermode parameter. This sets the default frequency for all FXS ports on the card. The default may be overridden on individual ports by using the ringfreqX=YY parameter, where X is the port number (1-4), and YY is the frequency (17, 20, 25, 30, 33, 40, 42, 50, 54, 60, or 67). The opermode and ringfreq overrides must be set when loading the module; this is done in /etc/modprobe.d/dahdi or /etc/modprobe.conf depending on your distro. The fxshonormode option needs to be set to 1, and it is a good idea to set boostringer to 1 as well.

Mode	Frequency
FCC17	16.67 Hz
FCC	20 Hz (default)
FCC25	25 Hz
FCC30	30 Hz
FCC33	33.33 Hz
FCC40	40 Hz
FCC42	42 Hz
FCC50	50 Hz
FCC54	54 Hz
FCC60	60 Hz
FCC67	66.66 Hz

To set 50 Hz ringing as default, with 30 Hz on port 4: