DAHDI Telephony Interface Driver

First come the span definitions, in the format

All T1/E1/BRI spans generate a clock signal on their transmit side. The <timing source> parameter determines whether the clock signal from the far end of the T1/E1/BRI is used as the master source of clock timing. If it is, our own clock will synchronise to it. T1/E1/BRI connected directly or indirectly to a PSTN provider (telco) should generally be the first choice to sync to. The PSTN will never be a slave to you. You must be a slave to it.

Choose 1 to make the equipment at the far end of the E1/T1/BRI link the preferred source of the master clock. Choose 2 to make it the second choice for the master clock, if the first choice port fails (the far end dies, a cable breaks, or whatever). Choose 3 to make a port the third choice, and so on. If you have, say, 2 ports connected to the PSTN, mark those as 1 and 2. The number used for each port should be different.

If you choose 0, the port will never be used as a source of timing. This is appropriate when you know the far end should always be a slave to you. If the port is connected to a channel bank, for example, you should always be its master. Likewise, BRI TE ports should always be configured as a slave. Any number of ports can be marked as 0.

Incorrect timing sync may cause clicks/noise in the audio, poor quality or failed faxes, unreliable modem operation, and is a general all round bad thing.

The line build-out (or LBO) is an integer, from the following table:

If the span is a BRI port the line build-out is not used and should be set to 0.

Next come the dynamic span definitions, in the form:

Where <driver> is the name of the driver (e.g. eth), <address> is the driver specific address (like a MAC for eth), <numchans> is the number of channels, and <timing> is a timing priority, like for a normal span. use "0" to not use this as a timing source, or prioritize them as primary, secondard, etc. Note that you MUST have a REAL DAHDI device if you are not using external timing.

If a non-zero timing value is used, as above, only the last span should have the non-zero value.

Next come the definitions for using the channels. The format is: <device>=<channel list>

Valid devices are:

The channel list is a comma-separated list of channels or ranges, for example:

So, some complete examples are:

An example of BRI port:

Finally, you can preload some tone zones, to prevent them from getting overwritten by other users (if you allow non-root users to open /dev/dahdi/* interfaces anyway. Also this means they won’t have to be loaded at runtime. The format is "loadzone=<zone>" where the zone is a two letter country code.

You may also specify a default zone with "defaultzone=<zone>" where zone is a two letter country code.

An up-to-date list of the zones can be found in the file zonedata.c

(see http://www.zapatatelephony.org/app_rpt.html)

The PCI Radio Interface card interfaces up to 4 two-way radios (either a base/mobile radio or repeater system) to DAHDI channels. The driver may work either independent of an application, or with it, through the driver;s ioctl() interface. This file gives you access to specify load-time parameters for Radio channels, so that the driver may run by itself, and just act like a generic DAHDI radio interface.

Unlike the rest of this file, you specify a block of parameters, and then the channel(s) to which they apply. CTCSS is specified as a frequency in tenths of hertz, for example 131.8 HZ is specified as 1318. DCS for receive is specified as the code directly, for example 223. DCS for transmit is specified as D and then the code, for example D223.

The hardware supports a "community" CTCSS decoder system that has arbitrary transmit CTCSS or DCS codes associated with them, unlike traditional "community" systems that encode the same tone they decode.

this example is a single tone DCS transmit and receive

specify the transmit tone (in DCS mode this stays constant):

specify the receive DCS code:

this example is a "community" CTCSS (if you only want a single tone, then only specify 1 in the ctcss list)

specify the default transmit tone (when not receiving):

Specify the receive freq, the tag (use 0 if none), and the transmit code. The tag may be used by applications to determine classification of tones. The tones are to be specified in order of presedence, most important first. Currently, 15 tones may be specified..

The following parameters may be omitted if their default value is acceptible

Set the receive debounce time in milliseconds:

set the transmit quiet dropoff burst time in milliseconds:

set the COR level threshold (specified in tenths of millivolts) valid values are {3125,6250,9375,12500,15625,18750,21875,25000}

Invert COR signal {y,n}

Set the external tone mode; yes, no, internal {y,n,i}

Now apply the configuration to the specified channels:

We are all done with our channel parameters, so now we specify what channels they apply to

Usually the channel driver sets the encoding of the PCM for the channel (mulaw / alaw. That is: g711u or g711a). However there are some cases where you would like to override that. mulaw and alaw set different such encoding. Use them for channels you have already defined with e.g. bchan or fxoks.

deflaw is similar, but resets the encoding to the channel driver’s default. It must be useful for something, I guess.

DAHDI uses modular echo cancellers that are configured per channel. The echo cancellers are compiled and installed as part of the dahdi-linux package. You can specify in this file the echo canceller to be used for each channel. The default behavior is for there to be NO echo canceller on any channel, so it is very important that you specify one here.

Valid echo cancellers are: hwec, mg2, kb1, sec2, and sec. hwec is a special echo canceller that should be used if hardware echo cancellation is desired on and available on the specified channels. If compiled, hpec is also a valid echo canceller.

To configure the default echo cancellers, use the format: echocanceller=<echocanceller name>,<channel(s)>

Example: Configure channels 1 through 8 to use the mg2 echo canceller

And change channel 2 to use the kb1 echo canceller.