Call Today 716.688.4675

V.90 Modem Software

V.90 Modem

V.90 enables communications between an analog and a digital modem using V.34 and G.711 PCM

V.90 modem software implements ITU V.90 Recommendation which defines procedures between a “digital” and an “analog” modem. The analog device, which may be connected to the PSTN through either an analog or digital interface, transmits V.34 signals and receives G.711 PCM signals. The digital device, which is connected to the PSTN through a digital interface, transmits G.711 PCM signals and receives V.34 signals. Contact us to discuss your V.90 modem application.

download brochure


Virtual Modem over IP

VOCAL’s SIP Software modem (MoIP or V.MoIP) solution provides developers a range of solutions to connect legacy dial up modems to modem infrastructure. Unlike other virtual modem designs, the SIP software modem can communicate with a physical modem at the far end using a VoIP service over an IP network.



VOCAL’s V.90 modem software is optimized for performance on leading DSP architectures and processors from TI, Intel, ADI, ARM and other vendors. Our software  may be licensed standalone, as a library or complete design. Custom solutions are also available to meet your specific V.90 modem requirements.

V.90 Features

  • Modem MIB Support (RFC 1696).
  • 22 modulation rates from 28000 bps to 56000 bps in increments of 1.333 kbps. (Administration requirements may restrict maximum rates/power allowed).
  • Multi-tasking environment compatible.

V.90 SoftModem

VOCAL’s V.90 softmodem uses state-of-the-art line probing analysis to automatically determine maximum channel capacity. There are 22 modulation rates in range of 28 kbps to 56 kbps, in increments of 1.333 kbps. The V.90 soft modem also supports MSE fallback/fallforward threshold control to adjust the tradeoff between higher data channel rates and symbol error rates. Our field proven V.90 design has been rigorously tested with commercial standalone servers and clients, based on the ITU and TIA recommendations ITU V.56bis, V.56ter, TIA TSB37A and TSB38.

Depending upon the V.90 configuration selected, the line interface 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 this software can provide PPP, V.14, HDLC or direct binary framing layers. The higher data protocol layers, V.42 (including MNP 2-4), V.44, V.42bis and MNP5, are options as well.

The V.90 modulation family can be combined with other data modulations (V.92, V.34, V.32bis/V.32, and V.22bis/V.22/V.23/V.21). V.8/V.8bis startup procedures can be used. Our V.90 modem software is fully compatible with VOCAL’s facsimile, telephony, speech coder and multimedia systems.

V.90 Modem Block Diagram

V.90 Soft Modem Block Diagram

VOCAL’s V.90 software design supports analog-digital modem configurations


  • As per terminology above, three V.90 modem system configurations are relevant:
    • analog modem only
    • digital modem only
    • either analog or digital modem
  • Analog modem DAA interface using linear codec at 16.0 kHz sample rate.
  • Digital modem direct interface to 8.0 kHz PCM data stream (A-law or μ-law).
  • PPP (RFC1662), V.14, HDLC and direct binary framing layers available.
  • North American and International Dialing/Telephony functions available.
  • DTMF detection during voice modes available.
  • Data protocol layer (V.42/MNP2-4/V.44/V.42bis/MNP5) available.
  • System can be combined with V.110 rate adaptation software.
  • System can be combined with other modulations (V.92, V.34, V.32bis, et al.) and automode procedures(V.8bis, V.8 and PN-2330).
  • Data/Facsimile/Voice Distinction upon startup available.
  • Complete facsimile systems with modulations (V.34, V.17 et al.), protocols (T.30), and speech coders available.



VOCAL’s optimized software is available for the following platforms. Please contact us for specific V.90 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