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V.29 Fax Software

V.29 Fax Modem SoftwareV.29 fax software supports a 9600 bps modem used on point-to-point 4-wire leased telephony circuits. V.29 fax is available as a real-time implementation with support for multi-channel applications. Contact us to discuss your V.29 fax application requirements.

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VOCAL’s V.29 fax software is optimized for conventional processors and DSPs from TI, ADI, ARM, Intel and other vendors. The software libraries are modular and can be executed as a single task under a variety of operating systems or standalone with its own microkernel. Our V.29 fax software is available standalone, as part of an embedded library, or as a complete design. Custom solutions are also available.

V.29 Fax Software Features

  • Fully compliant with ITU V.29 recommendations
  • Modular software suite available with controller code
  • Optimized for high performance on leading edge DSP architectures
  • Multi-tasking environment compatible
  • Multichannel implementation

V.29 Fax

ITU-T V.29 defines the modulation methods and operating sequences for a 9600 bps modem used primarily for use on point-to-point 4-wire leased telephony circuits. Data transmission is at 9.6 kbps, with fallback rates of 7.2 kbps and 4.8 kbps, with symbol rate of 2400 symbols per second. V.29 fax may operate in either full duplex or half-duplex mode.

All of the V.29 fax modulations and data streams can be controlled with VOCAL’s T.30 library or with VOCAL’s facsimile service Class 1 Command Set(EIA-578 and T.31). The T.30 library could in turn be controlled by VOCAL’s facsimile service Class 2 Command Sets T.32 (Fax Class 2.1), EIA-592 (Fax Class 2.0), or industry standard (Fax Class 2). With Fax Class 1, most of the protocol is executed in software, with the advantage that any changes don’t require hardware modifications. This is in contrast to Class 2, where image processing is handled by the modem.

The line interface for V.29  fax may be an analog front end (codec and DAA) or a digital interface such as T1/E1, Switched 56, and ISDN. The upper end of the V.29 fax software offers a direct binary and HDLC interface.


  • DAA interface using linear codec at 7.2 kHz, 8.0 kHz or 16.0 kHz sample rate
  • Direct interface to 8.0 kHz PCM data stream (A-law or μ-law)
  • North American and International Dialing/Telephony dialing functions available
  • DTMF detection during voice modes available
  • Facsimile protocol layer (T.30 with ECM/BFT) available
  • Facsimile service class 1 command sets (T.31 and EIA-578) available
  • Facsimile service class 2 command sets (T.32, EIA-592 and industry standard fax class 2) available.
  • System can be combined with V.34fax facsimile modulations and startup procedures (V.8 and V.8bis).



VOCAL’s optimized fax software is available for the following platforms. Please contact us for specific V.29 fax supported platforms.

Processors Operating Systems
  • Texas Instruments – C6000 (TMS320C62x, TMS320C64x, TMS320C645x, TMS320C66x, TMS320C67x), DaVinci, OMAP, C5000 (TMS320C54x, TMS320C55x)
  • Analog Devices – Blackfin, ADSP-21xx, TigerSHARC, SHARC
  • PowerPC
  • MIPS – MIPS32, MIPS64, MIPS4Kc
  • ARM – ARM7, ARM9, ARM9E, ARM10E, ARM11, StrongARM, ARM Cortex-A8, Cortex-M1
  • Intel / AMD – x86, x64 (both 32 and 64 bit modes)
  • Google Android
  • Apple iOS / iPhone / iPad & MacOS
  • Unix,  Linux, μClinux, BSD
  • Microsoft Windows ACM / RTC / CE / Mobile
  • Symbian
  • eCOS / eCOSPro
  • Wind River VxWorks
  • Green Hills Integrity
  • Micrium μCOS
VOCAL Technologies, Ltd.
520 Lee Entrance, Suite 202
Amherst New York 14228
Phone: +1-716-688-4675
Fax: +1-716-639-0713