Telefoni-konverter
G.711 u-law, A-law, 8 kHz mono
Om dette verktøyet
Phone systems are stuck in narrowband. A PSTN call carries roughly 300-3400 Hz of audio at an 8 kHz sample rate, and almost every PBX, IVR and contact-center platform will reject or silently mangle a 44.1 kHz stereo MP3. This converter takes whatever you recorded - a voiceover, a Zoom export, a phone memo, a video - and produces the exact file your phone platform expects: G.711 u-law, G.711 A-law, 8 kHz mono PCM WAV or Asterisk's raw sln.
u-law is the companding standard on North American and Japanese networks; A-law is used in Europe and most of the rest of the world. Both squeeze 14 bits of dynamic range into 8 bits per sample at 64 kbps, which is why a G.711 file sounds exactly like a phone call. If your platform documents 16 kHz wideband prompts (HD voice), use the 16 kHz PCM preset instead.
The optional normalization pass levels the prompt to around -19 LUFS with a -3 dBTP ceiling. That matters more on a phone line than in music: narrowband codecs distort ugly when fed hot peaks, and a prompt recorded too quietly disappears under line noise. As with every Privvert tool, FFmpeg runs as WebAssembly inside your own browser - your recordings, customer names and internal prompts are never uploaded anywhere.
Funksjoner
- G.711 u-law and A-law, both in WAV containers and headerless raw
- 8 kHz mono 16-bit PCM WAV - the safest universal IVR upload format
- 16 kHz mono PCM WAV for wideband / HD voice platforms
- Asterisk sln (raw signed linear 8 kHz) output
- Automatic downmix to mono and resample to 8 kHz
- Optional loudness normalization tuned for narrowband playback
- Accepts audio and video sources - the audio track is extracted
- Browser-only processing, no signup, no upload
Slik bruker du det
- Drop in your recording (audio or video).
- Pick the format your phone system documents - G.711 u-law in North America, A-law in Europe, or 8 kHz PCM WAV if you are unsure.
- Leave normalization on unless your prompt is already leveled.
- Click Convert and upload the downloaded file to your PBX, IVR or trunk provider.
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Ofte stilte spørsmål
u-law (mu-law) is the G.711 variant used in North America and Japan. A-law is used across Europe, Africa, Asia-Pacific and South America. If your provider does not say, 8 kHz mono 16-bit PCM WAV is accepted almost everywhere and the switch will transcode it itself.
A traditional phone call samples audio at 8 kHz in a single channel. Anything higher is discarded in the network. Uploading a 44.1 kHz stereo file often produces a rejected upload, chipmunk playback, or audio that plays at the wrong speed because the platform assumed 8 kHz.
It will sound like a phone call, because that is what it becomes. G.711 keeps 300-3400 Hz and drops everything else. Record close to the mic, avoid heavy music beds and keep sibilance under control - detail above 3.4 kHz will not survive the codec.
sln is Asterisk's internal raw format: headerless 16-bit little-endian PCM at 8 kHz. Asterisk can play it with zero transcoding cost, which is why high-traffic dialplans often store prompts as sln.
Yes. Twilio and Amazon Connect accept 8 kHz mono WAV (u-law or 16-bit PCM), and Genesys accepts the same. Check the platform's current docs for the exact preset, then pick it here.
No. The conversion runs in your browser through FFmpeg compiled to WebAssembly. Nothing leaves your device, which matters when the prompt contains internal extensions, customer names or unreleased branding. See our piece on the risks of online file converters for why that distinction is not cosmetic.