Direct answer
G.711 μ-law is a telephony audio encoding with one eight-bit codeword per sample. In a classic RIFF/WAVE file, μ-law is identified by numeric WAV format tag 0x0007. At 8,000 samples per second and one channel, it is the canonical telephony layout required or preferred by several IVR platforms—but the surrounding WAV container still matters for file-upload targets.
PCM and μ-law are not interchangeable
| Layout | What each sample stores | Why the distinction matters |
|---|---|---|
| 16-bit PCM WAV | A signed linear amplitude value | Two bytes per channel sample |
| 8-bit PCM WAV | An unsigned linear amplitude value | One byte, but it is not G.711 |
| G.711 μ-law WAV | A logarithmically companded codeword | One byte identified by format tag 0x0007 |
Saying “8-bit WAV” is therefore incomplete. An 8-bit PCM file and an 8-bit μ-law file use different numeric sample representations and different WAV codec identities.
Why 8 kHz mono μ-law is approximately 64 kbps
An 8 kHz mono μ-law stream stores 8,000 samples each second, one byte per sample, on one channel. That is 8,000 × 8 bits, or about 64,000 bits per second of audio payload. A WAV file is slightly larger because RIFF chunk identifiers, sizes, format fields, padding, and other optional chunks sit around the payload.
How IVRReady checks a μ-law WAV
- 1. Read the RIFF/WAVE structure and bounded chunk declarations from the actual bytes.
- 2. Resolve the numeric codec identity instead of trusting a filename or extension.
- 3. Read sample rate, channel count, audio-data bounds, and any target-specific limits.
- 4. Classify source compatibility separately from signal-level QA.
- 5. Reinspect generated WAV bytes after correction; a successful FFmpeg exit is not proof.
How μ-law relates to IVRReady target packs
| Target | μ-law role | Checker |
|---|---|---|
| Amazon Connect | Requires a strict canonical μ-law WAV upload proven from its numeric fields. | Open checker |
| Webex Contact Center | Requires a strict canonical μ-law WAV upload proven from its numeric fields. | Open checker |
| NICE CXone | Requires a strict canonical μ-law WAV upload proven from its numeric fields. | Open checker |
| Genesys Cloud Architect | Accepts a documented WAV matrix; μ-law is the preferred canonical form and one accepted layout. | Open checker |
| Talkdesk Greetings | Accepts the WAV container in IVRReady's current coverage and transcodes on the platform. | Open checker |
| Twilio Media Streams | Uses a verified μ-law WAV only as an intermediate, then delivers headerless raw media. | Open checker |
Continue with the delivery details
A μ-law WAV is an uploadable file for some targets, but Twilio Media Streams requires the raw payload inside it. Read the WAV-to-Twilio guide or compare every target in the contact-center requirements guide.