Metering
Voice AI runs on a credit-based prepaid model. Every account is provisioned a Lago wallet on signup, seeded with free credits, and replenished by top-ups or plan renewals.
Authorisation against the wallet is enforced in real time at the gateway, backed by Redis with sub-millisecond latency. Calls without sufficient credit fail fast with 402 Payment Required rather than running and being billed retroactively.
Per-API measurement units
Each API has its own natural unit. Credits are debited at the published per-unit rate when the call completes successfully. Failed calls are not billed.
| API | Unit | Notes |
|---|---|---|
| Speech-to-Text | Seconds of audio submitted | Rounded up to the nearest second per request. |
| Text-to-Speech | Characters of input text | Whitespace and punctuation included. |
| Transcriptions | Seconds of audio submitted | Same rate as Speech-to-Text; diarization included. |
| Voice Clone | Requests | One credit-priced request per clone, irrespective of sample length. |
| Voice Design | Requests | One credit-priced request per generated voice. |
| Speech Translation | Seconds of audio submitted | Includes translation; no separate text fee. |
| Text Translation | Characters of source text | Output length not billed separately. |
| Reasoning | Tokens (input + output) | Standard tokenizer; reported in the response body. |
| Speech-to-Speech | Seconds of audio submitted | Patent-pending pricing tier. |
| Streaming Text | Tokens (input + output) | Streaming has no surcharge over Reasoning. |
| Language Intelligence | Requests | Single credit-priced request per call. |
| Knowledge & Memory | Requests | Indexing and retrieval each priced separately. |
The current per-unit rate for your plan is shown on the Console pricing page.
Free credits
Every new account receives a free credit grant on signup. The grant is scoped to the Voice AI wallet and does not transfer to Universal API.