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Data Modem

Data Modulations & ProtocolsVOCAL’s Data Modem solutions comprise a range of data modulations and protocols for legacy modem applications and modem communications over PSTN, radio, mobile, satellite and other networks. VOCAL’s SIP Analog Modem Server (SAMS) allows M2M modems to be used with SIP infrastructure – from the Cloud. VOCAL provides:

  • V.34, V.22, V.32, V.90, V.91 and V.92 data modulations
  • V.42 and V.44 data protocols
  • V.59 diagnostics
  • Remote modem access
  • Optimized for DSP, ARM, X86 and other processors

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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 data modem source code is optimized for performance on leading DSP architectures and processors from TI, Intel, ADI, ARM and other leading vendors. The data modem 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 modem software may be licensed standalone, as a library or a complete design. Custom solutions are also available to meet your specific modem requirements.  Contact us to discuss your data modem application.

Data Modulations

Automatic modulation determination procedures (Automode) include V.8, V.8bis and PN-2330. V.92/V.90 digital client is also available for specialized server requirements (i.e. self-test), as well as analog client V.92/V.90 support.

Data Protocols

  • V.42 LAPM Error Correction, Detection
  • V.42bis Lempel-Ziv Data Compression
  • V.44 LZJH Data Compression
  • MNP 2-4 Error Correction
  • MNP 5 Data Compression
  • MNP 10 Protocol Extensions for Cellular

The higher data protocol layers include V.42 (including MNP2-4), V.42bis, V.44 and MNP-5. PPP framing support is provided as a runtime option. The application interface of this software can support an industry standard AT command set or may be used directly by an application. The modulation layer of this software can provide a HDLC, V.14 or a direct binary framing layer. The line interface may be an analog front end (codec and DAA) or a digital interface such as T1/E1, xDSL, ATM, and ISDN.

Remote Access Server

The base Remote Access Server (RAS) modem supports the following features on a per channel basis:

  • V.90 Server at 28000 to 56000 bps
  • V.34 at 4800 to 33600 bps
  • V.32bis/V.32 at 4800 to 14400 bps
  • V.22bis at 2400 bps
  • V.22/Bell 212 at 1200 bps
  • V.23/Bell 202 at 1200/75
  • V.21/Bell 103 at 300 bps
  • V.42 LAPM error correction
  • V.42bis BTLZ compression
  • V.44 Data compression
  • MNP 2-4 error correction
  • MNP 5 compression
  • Diagnostic support for modem MIB
  • V.59 modem diagnostic/status software

Data Modem Monitoring and Diagnostics

Data modem monitoring and diagnostics features per-channel frame statistic continuously updated while operating. The driving application can access the data modem statistics for monitoring system performance and network bandwidth. Additional diagnostic signaling can be selected for troubleshooting integration and system issues. The statistics available include:

  • Modulation State
  • SNR MSE Measure
  • Tx/Rx Level dBm
  • Telemetry Data Update
  • Data Modulation Monitor Retrain/Renegotiate
  • Carrier Family
  • Disconnect Reason
  • Initial Tx/Rx Data Rate
  • Current Tx/Rx Data Rate
  • IETF Modem MIB support
  • V.59 Modem diagnostic support


VOCAL Technologies, Ltd.
520 Lee Entrance, Suite 202
Amherst New York 14228
Phone: +1-716-688-4675
Fax: +1-716-639-0713