GSM to CAF Converter
Processing entirely on your device — large files may take a moment.
GSM 06.10 Speech and Core Audio Format exist for different jobs: GSM 06.10 is the 1990s mobile-telephony speech codec — 13 kbit/s audio that VoIP systems and old answering machines still emit. Convert CAF files to WAV or MP3 for use outside the Apple ecosystem.
Because the whole conversion happens on your device, it is instant, unlimited and genuinely private — no accounts, no watermarks, no files on anyone's server. Multiple files are converted in one go.
How GSM compares to CAF
| GSM | CAF | |
|---|---|---|
| Structure | Raw GSM frames (33 bytes/20ms) | caff header + chunk table |
| Types / schema | Lossy speech codec (RPE-LTP) | PCM/ALAC/AAC in CAF |
| Compatibility | Asterisk, SoX, ffmpeg | afconvert, Logic Pro, ffmpeg |
| Best for | Telephony recordings | Apple pro-audio workflows |
How to convert GSM to CAF
- 1
Select your files
Drag & drop your GSM files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to CAF". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted CAF file individually, or grab everything at once as a ZIP archive.
About the GSM format
GSM 06.10 is the speech codec of the original GSM mobile network — 13 kbit/s RPE-LTP that made digital cellphone calls possible in 1991 and still lives inside VoIP systems, old answering machines and Asterisk PBX recordings.
It is lossy speech, not music: converting GSM to WAV or MP3 preserves intelligibility perfectly while finally letting desktop players open the file without special codecs.
+ Strengths
- ✓Tiny bitrate for speech intelligibility
- ✓Ubiquitous in telephony systems
- ✓Decodes natively via ffmpeg
! Limitations
- −Speech-only quality — music falls apart
- −13 kbit/s artifacts are audible
- −8000 Hz sample rate only
About the CAF format
CAF (Core Audio Format) is Apple's container for pro audio: 64-bit file offsets for recordings of any length, any codec as payload (PCM, ALAC, AAC), and time-stamped MIDI-style event chunks. Logic Pro exports it and macOS system sounds ship in it.
ffmpeg decodes the common PCM/ALAC payload variants, converting CAF to WAV or MP3 for use in any non-Apple DAW, player or web player.
+ Strengths
- ✓64-bit offsets — no size ceilings
- ✓Native to Logic Pro pipelines
- ✓Flexible codec payload
! Limitations
- −Apple-centric — rare outside macOS
- −Some CAF variants (UUID chunks) unsupported
- −Tag metadata Apple-specific
Why convert GSM to CAF?
Think of it as moving your file to the container that fits the job. Speech-only quality — music falls apart CAF works differently: 64-bit offsets — no size ceilings If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this GSM to CAF converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for GSM to CAF?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Can I convert a whole folder of GSM files?
You can select many files at once and they are processed in a single batch. Output files land in one ZIP download when there is more than one result.
Are tags like title and artist preserved?
Tag handling varies between target formats and this conversion focuses on the audio itself. For archival copies where tags matter, keep the original file; the converted copy is for playback and sharing.