Zapata -- PC-Based High Density Computer Telephony Project

Current computer telephony technologies have 2 main problems: ludicrously high cost, and ludicrously low support.

When you buy standard commercially-available computer telephony hardware these days, after having your wallet absolutely raped, you find that the product is broken, or at least has funny quirks that even the manufacturer doesn't seem to know about (or care) about, and isn't interested in (or for that matter capable of) giving you any reasonable level of support. This is completely consistent (without exception) among all of the major manufacturers.

There is now finally hope after 15 years of this type of severe dysfunction.

The Zapata project, named after the famous Mexican Revolutionary, is an attempt to address these issues in a practical and livable manner.

After much experimentation, it was found that it was quite feasible to achieve somewhat high channel-count density utilizing minimal hardware on a modern PC-style system, thus minimizing the hardware costs.

In addition, a free open-source architecture running on a solid, stable, free open-source platform (Linux or FreeBSD), completely eliminates support issues. This way, if you don't like what it does or the way it does it, you can 'fix' it yourself. Unlike many of the commercial manufacturers, we have nothing to hide or lose by making our technology and source code openly available to everyone.

The Zapata Technology

The Zapata technology combines an interface card, called "Tormenta" (which means "storm") which we developed, a driver for this card for the Linux or FreeBSD operating system, and an API library for user-interface.

The original Zapata interface card ("Tormenta") is a 16-bit ISA bus card (that occupies 4096 bytes of system memory space), containing interface hardware for two T-1 digital 1.544 MBPS (or two E-1 digital 2.048 MBPS) telephone interfaces. It contains merely the minimal amount of hardware necessary, thus keeping the costs to a bare minimum. It contains no DSP or proprietary technology, whatsoever. It really pushes the ISA bus (from a throughput standpoint) to its limits.

The new Zapata interface card ("Tormenta 2 PCI") is a 32 bit PCI bus card, containing interface hardware for four T-1 digital 1.544 MBPS (or E-1 2.048 MBPS) telephone interfaces. Like the original ISA card, it contains merely the bare minimal amount of hardware necessary, keeping costs and harware complexity (and size in this case, being that the card is about 3 1/2 inches high and 5 inches long) to a minimum.

"We don't need no stinkin' DSP!!"

The driver and library fully implement all standard telecom functions, including signaling, DTMF and MF detection and generation, arbitrary single and dual tone generation, Caller*ID generation (on FXO channels) Caller*ID reception (on FXS channels), voice play and record, switching, and conferencing (yes, it REALLY IS possible to use your Unix box as a DSP!!), yet consumes quite minimal system resources. It currently supports chanelized µ-law T-1 services (robbed-bit (also known as channel-associated) signaling). E & M and FXO/FXS (both loopstart and groundstart) signaling are currently supported, in addition to A-law/CCS signalling for Euro-ISDN (the hardware-level drivers handle CAS on an E-1, but there is no user interface for this yet). Also, Primary Rate ISDN (Both North American and Euro ISDN, with external library), and data and networking (HDLC) modes are supported in Linux driver/library only.

In addition, Zapata fully implements Digital TTY/TDD modems within its library, making it the first ever multiple-line telecommunications solution for communicating with Deaf and hearing-impared people on a large-scale basis. Nothing else has ever even come close (the highest density devices to date have been single analog line based) at any price.

And it's all freely available as open-source.

There are also sample applications included, particularly the "Emiliano" MIPL browser/interpreter. This is a fully functional voice-recorded telephonic MIPL browser (both voice and TTY/TDD), implemented using the Zapata technology for the telephone interface.

Hardware Availability

Both the PCI and ISA cards are currently available from third-party sources. Please contact us via email for more information.


This technology and hardware is fully compliant with AT&T PUB 43801 and other standards for channelized T-1 interfaces. It will function quite well in the United States and any other country that has the same technical standards as the US, and in a number of other countries as well.

Also, it contains CSU (Channel Service Unit) functionality, which is required by many local telephone providers, thus even further reducing the relative cost. Most of the commonly-available digital telephony cards do not come with this functionality, and require it to be provided by an external adjunct CSU device.

The external Primary Rate ISDN library currently supports voice calls in both CPE (user side) and Network-side configurations with the National ISDN (NI-2) protocol, Nortel DMS-100 custom protocol, Lucent 5ESS custom protocol (theoretically also the AT&T 4ESS protocol, although not tested), and ETSI Euro-ISDN, implementing the Q.921 data-link layer (d-channel) and Q.931 call-control layer. This library is currently only available under Linux.

"ˇViva Zapata!"


Click here for current "Zapata" Project status

Click here for Zapata Technology Design Philosophy


Click here to download the current BSD software distribution (driver, library, browser application)

Click here to download the current LINUX software distribution (driver, library, browser application)

Click here to view the schematics and board artworks for the Tormenta ISA PC Card, Rev. A

Click here to view the current Zapata library source (with documentation)

Click here to view the current Zapata library header file

Click here to view the current Tormenta driver source (with documentation)

Click here to view the current Tormenta header file

Click here to view the Tormenta switching/conferencing architecture

Click here to view the Tormenta driver installation instructions


With the exception of items protected by the GNU General Public License (which are clearly indicated as such), the technologies, software, hardware, designs, drawings, schematics, board layouts and/or artwork, concepts, methodologies (including the use of all of these, and that which is derived from the use of all of these), all other intellectual properties contained herein, and all intellectual property rights have been and shall continue to be expressly for the benefit of all mankind, and are perpetually placed in the public domain, and may be used, copied, and/or modified by anyone, in any manner, for any legal purpose, without restriction.