GSM Won't Open? Convert to AU Instantly
Fast, instant GSM to AU conversion. No signup required. Just drop your .gsm file and get .au in seconds.
Batch Settings
About GSM to AU Conversion
Dealing with a GSM file that won't open on your device? You're not alone — GSM compatibility issues are one of the most common reasons people search for a file converter. GSM is a widely used file format.
The fix is simple: convert your GSM to AU. AU is a widely used file format. This conversion lets you convert between formats quickly, solving the problem in seconds rather than hours of troubleshooting.
Converting GSM to AU maintains high quality with CocoConvert's optimised encoder settings.
CocoConvert processes your GSM file on secure servers in Germany — upload, convert, download. Your files are encrypted via TLS and automatically deleted within 24 hours. No account needed, no software to install, and it works on any device with a browser.
This conversion is ideal when you When you need a AU file.
The conversion engine behind CocoConvert uses FFmpeg, Sharp, and qpdf — the same open-source libraries trusted by Netflix, YouTube, and enterprise platforms. Pro users can batch convert up to 100 files at once.
How to Convert GSM to AU
- 1
Add your GSM file
Drag and drop your .gsm file into the converter, or tap "Browse" to pick it from your device. Multiple files are supported for batch processing.
- 2
Pick AU output
Select .au as the target format. CocoConvert automatically applies the best quality settings for this conversion.
- 3
Start conversion
Hit the Convert button. The audio engine processes your file server-side — no CPU drain on your device.
- 4
Save your file
Once done, download your .au file. For batch jobs, download all at once as a zip.
What Happens When You Convert GSM to AU
Your GSM file is decoded and re-encoded as AU.
Your GSM file is uploaded and validated
The file is decoded (parsed into its raw data)
The data is re-encoded in AU format
The converted file is ready for download
Format Comparison
GSM
.gsm file
| Extension | .gsm |
| MIME Type | audio/gsm |
| Category | Audio |
AU
.au file
| Extension | .au |
| MIME Type | audio/basic |
| Category | Audio |
Should You Convert GSM to AU?
When to Convert
- ✓When you need a AU file
Frequently Asked Questions
Why won't my GSM file open?
GSM files may not open if your device lacks the right codec or application. Converting to AU — a more widely supported format — usually resolves this. AU is a widely used file format.
Is it safe to convert GSM to AU online?
Yes. CocoConvert encrypts your file via TLS, processes it on isolated servers in Germany, and permanently deletes it within 24 hours. Your files are never shared or analysed.
Will I lose quality converting GSM to AU?
Converting GSM to AU maintains high quality with CocoConvert's optimised encoder settings. CocoConvert uses high-quality encoder defaults to preserve as much fidelity as possible.
How large can my GSM file be?
Free users can convert files up to 250 MB each. Pro users get a 5 GB limit per file, and Business API users have custom limits.
Can I convert GSM to AU on my phone?
Absolutely. CocoConvert works in any modern browser — iOS Safari, Android Chrome, and all desktop browsers. No app required.
Versions are pinned in our worker Dockerfile and re-built via CI on every change.