G.726 / ADPCM WAV Won’t Play in Gmail — Here’s the Fix
Your .wav voicemail is encoded with G.726 (an ADPCM telephony codec), and Gmail won’t play it. Like other phone-system formats, it’s not something browsers can decode. Here’s how to play it inline.
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What G.726 / ADPCM is
G.726 is an Adaptive Differential PCM (ADPCM) codec used by carriers and PBX systems to compress voice to a fraction of its original size. It’s efficient for telephony, which is why some voicemail-to-email systems wrap it in a WAV file.
But ADPCM telephony variants aren’t supported by browsers. When the file reaches Gmail, the built-in player recognises the .wav container but has no decoder for the G.726 audio inside it — so playback silently fails.
Confirm it
The fix: play G.726 inline in Gmail
Gmail Audio Player decodes G.726/ADPCM directly in your browser via a bundled WebAssembly engine. It detects the attachment, converts the audio to standard PCM locally, and shows a working player inside the email — no conversion, no download, no uploads.
Install it once and G.726 voicemails play inline, with scrubbing, speed control, and optional AI transcription on paid plans.
Frequently asked questions
What is G.726?
G.726 is an ADPCM telephony codec that compresses voice to 16–40 kbps. Carriers and PBX systems use it to save bandwidth on voicemail and call recordings.
Why won't it play in Gmail?
Like other telephony codecs, G.726/ADPCM isn't part of the web media stack, so browsers don't include a decoder. Gmail's built-in player can't decode the audio even though the WAV file is valid.
How do I confirm it's G.726?
Open the file in VLC → Tools → Media Information → Codec. Look for "ADPCM" or "G.726". If it plays in VLC but not Gmail, it's a telephony codec.
Is my audio uploaded to play it?
No. Gmail Audio Player decodes G.726 locally in your browser. The audio stays on your machine for basic playback.
Related fixes
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