SPX to DVMS Converter

Convert Speex speech recordings to DVMS voice format

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Voice Mail Format

Convert Speex VoIP recordings to DVMS — a format used in voice messaging and telephony mail systems.

Browser-Based

No telephony software needed on your machine. Run the SPX to DVMS conversion from any web browser.

Files Stay Private

SPX uploads are removed after conversion. DVMS outputs are deleted within 24 hours.

How to convert SPX to DVMS

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose dvms or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your dvms file right afterwards

About formats

Speex is an open-source audio codec purpose-built for speech compression, developed by Jean-Marc Valin under the Xiph.Org Foundation. First released in October 2002, it targets voice-over-IP, conferencing, and any scenario where spoken word needs to travel efficiently over a network. SPX files wrap Speex-encoded audio inside an Ogg container, pairing the codec's speech optimization with Ogg's streaming capabilities. Three sampling rates are supported — narrowband at 8 kHz, wideband at 16 kHz, and ultra-wideband at 32 kHz — along with variable bitrate encoding that adapts in real time to speech complexity. A standout advantage is its patent-free, BSD-licensed nature, which allowed developers to embed it freely in both commercial and open-source products. Speex also bundles acoustic echo cancellation, noise suppression, and automatic gain control, features that rival codecs typically delegate to external libraries. Although its creators officially recommend Opus) as a successor since 2012, Speex remains deployed in legacy VoIP systems, archived recordings, and embedded devices where its lightweight decoder footprint is still valued.
Initial release: October 15, 2002
DVMS (Dutch Voice Messaging System) is a telephony-grade audio encoding born from the Netherlands' early push toward digital voicemail infrastructure. Deployed through KPN (formerly PTT Telecom) in the mid-1980s, the format stores mono voice data at a narrow 8 kHz sample rate, prioritizing compact message size over sonic breadth. Audio is compressed with a proprietary variant of logarithmic companding similar to European A-law encoding, squeezing recordings to roughly 8 kbit/s while keeping speech intelligible. Each file carries a small header identifying sample rate, compression type, and message metadata, which made automated routing across early PBX and voicemail systems straightforward. Although DVMS never gained traction outside Dutch telecom circles, it influenced how European carriers designed later voice messaging protocols. Tools like SoX and several legacy telephony libraries still read and write DVMS files, allowing archival playback of decades-old messages. Among its practical advantages: extremely small file sizes (a one-minute message occupies roughly 60 KB), reliable speech clarity despite aggressive compression, and a simple container layout that is easy to parse programmatically.
Developer: Dutch PTT Telecom
Initial release: 1984

Frequently Asked Questions

Why convert SPX to DVMS?

DVMS is used in certain voice messaging and telephony systems. Converting from SPX provides compatible audio for these platforms.

What is the DVMS format?

DVMS stores compressed voice data for telephony voice mail and messaging systems.

What opens DVMS files?

SOX and telephony voice mail systems can decode DVMS. Convert to WAV for playback in standard audio software.

Is voice quality acceptable?

DVMS is designed for speech — quality is comparable to telephone audio, which is sufficient for voice messaging.

Is it free?

SPX to DVMS conversion is free on convertio.tools.