The zaptel.conf file is not located with the other Asterisk .conf files; the Zaptel driver is available to any application that can make use of it, so it makes more sense to store it in a non-Asterisk-specific directory (/etc/). zaptel.conf is parsed by the ztcfg program to configure the TDM hardware elements in your system. You configure three main elements in the zaptel.conf file:
A way of identifying the interfaces on the card within the dialplan
The type of signaling the interface requires
The tone language associated with a particular interface, as found in zonedata.c
Be very careful not to plug your FXS module into a telephone line. The voltage associated with the phone line, especially during an incoming call, will be much too high for the module to handle and may permanently damage it, rendering it useless!
Within the zaptel.conf file, we define the type
of signaling that the channel is going to use. We also define which
channels to load. The options in the configuration file are the
information that will be used to configure the channels with the ztcfg command.
The actual parameters available in the zaptel.conf file are quite extensive, as a wide variety of PSTN interfaces make use of the Zaptel telephony engine. Also, as this technology is rapidly evolving, anything we write now may not be accurate by the time you read it. Consequently, we won’t try to list all of the options here.
In this book, we have focused on the Zaptel analog interfaces as provided by the Digium TDM400P card (see Chapter 3, Installing Asterisk).