> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> STT). Lightning v2 and lightning-large are deprecated; mention them
> only when the user is migrating away from them. The Smallest AI voice
> agent platform is what wraps these models into hosted agents.

# Voice Agents

## Entries

- [Atoms API: audit consolidation](https://docs.smallest.ai/changelog/voice-agents/2026/9/16.md): Consolidated corrections to the Atoms OpenAPI reference.
- [MCP: prompt-cache hit rate and per-turn LLM timings in debug_call, new get_latency_summary tool](https://docs.smallest.ai/changelog/voice-agents/2026/9/14.md): debug_call now returns the LLM-side numbers for a call alongside the caller-perceived latency it already reported: usage (prompt, completion and cached tokens
- [Call actions endpoints removed from API reference](https://docs.smallest.ai/changelog/voice-agents/2026/9/11.md): POST /call-actions, GET /call-actions, GET /call-actions/{id}, PUT /call-actions/{id}, and DELETE /call-actions/{id} are no longer part of the customer API su
- [PCA: aggregate limits on disposition metrics: combined prompt length and enum choices](https://docs.smallest.ai/changelog/voice-agents/2026/9/10.md): The Write to draft endpoint now enforces two aggregate limits when the payload includes postCallAnalyticsConfig.dispositionMetrics:
- [Inbound SIP trunks: connection details for every trunk](https://docs.smallest.ai/changelog/voice-agents/2026/9/9.md): Every inbound SIP trunk row on the SIP Trunks dashboard page now has a Connection details dialog.
- [Recordings: authenticated presigned-URL flow](https://docs.smallest.ai/changelog/voice-agents/2026/9/7.md): New endpoint documented: GET /atoms/v1/recordings/{callId}?channel=mono|dual returns a short-lived presigned S3 URL for the call's audio (atoms-platform#3625, Phase 1 of PRO-2775)..
- [Telephony rework: SIP trunks as resources, agents answer, calls choose their caller ID](https://docs.smallest.ai/changelog/voice-agents/2026/9/5.md): The telephony model is reorganized around one idea: *who answers a number* is durable configuration, *what a call dials from* is a property of the call.
- [New page: SIP Wire Reference](https://docs.smallest.ai/changelog/voice-agents/2026/9/3.md): New deep-dive page for SIP trunk integrators: SIP Wire Reference, linked from the SIP Trunking page.
- [SIP Trunking: UDP is accepted; the real hazard is fragmentation](https://docs.smallest.ai/changelog/voice-agents/2026/9/2.md): Correction to the 2026-08-28 transport contract.
- [API reference: schema and enum corrections against backend Zod validators](https://docs.smallest.ai/changelog/voice-agents/2026/9/1.md): Atoms and Waves API reference updated to match what the backend actually enforces.
- [Realtime Agent WebSocket: per-direction audio format contract](https://docs.smallest.ai/changelog/voice-agents/2026/8/28.md): The realtime voice-agent WebSocket API now has a documented contract for the audio you send and the audio the agent sends back.
- [Voice Agents API reference: Agents-first ordering, widget endpoints deprecated](https://docs.smallest.ai/changelog/voice-agents/2026/8/13.md): The API reference sidebar now opens with Agents at the top, followed by Calls, Campaigns, Phone Numbers, and Knowledge Base.
- [Voice Agents: Account, Web Call, and Campaign export endpoints on the API reference](https://docs.smallest.ai/changelog/voice-agents/2026/8/8.md): Six previously undocumented Voice Agents endpoints now render on the API reference:
- [SDK 5.5.0: typed errors, waves helpers, CLI expansion, crew custom-LLM gotcha, warm/cold transfer clarified](https://docs.smallest.ai/changelog/voice-agents/2026/8/6.md): Docs updates for the smallestai 5.5.0 release, plus the sibling platform fix for crew transfer audio.
- [New docs: smallestai agents CLI, expanded SDK overview, quickstart env + layout FAQs](https://docs.smallest.ai/changelog/voice-agents/2026/7/28.md): Three updates under Developer → Get Started.
- [Webhooks docs: signature verification, standard variables, deletion gate](https://docs.smallest.ai/changelog/voice-agents/2026/7/27.md): The Webhooks guide now documents behaviors previously only discoverable from the wire or from the platform source.
- [smallestai SDK - STT moves to the unified /waves/v1/stt endpoints; voice cloning + Electron LLM added](https://docs.smallest.ai/changelog/voice-agents/2026/7/25.md): The smallestai Python SDK is switching its Waves-side generator input from the legacy pulse-stt specs to the unified stt- specs, and picking up two Waves.
- [DNC endpoint restored in the OpenAPI spec](https://docs.smallest.ai/changelog/voice-agents/2026/7/24.md): GET /dnc is back in the Atoms OpenAPI spec.
- [Agent Versioning v2: branch and revision API (PRO-1789)](https://docs.smallest.ai/changelog/voice-agents/2026/7/23.md): Agent Versioning moves from the linear drafts + versions model to a branch + draft + revision model.
- [Agent Locking retired - superseded by Agent Versioning](https://docs.smallest.ai/changelog/voice-agents/2026/7/21.md): The Agent Locking feature is retired.
- [Voice Agents docs URL migration - atoms → voice-agents, atoms-platform → platform](https://docs.smallest.ai/changelog/voice-agents/2026/7/18.md): The Voice Agents product now lives under /voice-agents/ on the docs site, replacing the older /atoms/ prefix.
- [SIP termination URL - automatic normalization + corrected format guidance](https://docs.smallest.ai/changelog/voice-agents/2026/7/7.md): Importing your own phone number (POST /product/import-phone-number) is now forgiving about the SIP Termination URL format.
- [Realtime Agent - register-call token flow + streamed transcripts](https://docs.smallest.ai/changelog/voice-agents/2026/7/2.md): The Realtime Agent WebSocket reference now documents the recommended token flow for browser and client-side apps: call the new POST.
- [Realtime Agent - text-only chat mode](https://docs.smallest.ai/changelog/voice-agents/2026/6/23.md): The Realtime Agent WebSocket now supports a text-only session: open the connection with ?mode=chat to run a conversation with no STT, TTS, or audio.
- [AgentDTO - 19 customer-facing fields added to the `GET /agent/{id}` response schema](https://docs.smallest.ai/changelog/voice-agents/2026/6/22.md): The GET /atoms/v1/agent/{id} response was already returning these 19 fields at runtime (via the platform's response transformer), but the OpenAPI AgentDTO.
- [Python SDK 5.0.0 - method renames, new `calls` namespace, conversations sub-operations](https://docs.smallest.ai/changelog/voice-agents/2026/6/19.md): smallestai==5.0.0 ships a method-rename pass that aligns the auto-generated SDK with the canonical OpenAPI operation IDs.
- [Atoms API - Conversation cancel, recording URL, retries endpoints](https://docs.smallest.ai/changelog/voice-agents/2026/6/16.md): The Atoms OpenAPI spec now covers four customer-facing Conversations endpoints: POST /conversation/cancel (body-form), POST /conversation/{id}/cancel.
- [Versioning lifecycle developer guide + outbound caller-ID note](https://docs.smallest.ai/changelog/voice-agents/2026/6/11.md): A new developer-guide page documents the full create → draft → publish → activate flow against the public API in curl + Python, with the seven endpoints.
- [New endpoint - prompt scoring](https://docs.smallest.ai/changelog/voice-agents/2026/6/2.md): Pass exactly one of versionId (published version) or draftId (agent draft) in the request body.
- [Atoms API reference - iteration 1 updates](https://docs.smallest.ai/changelog/voice-agents/2026/5/29.md)
- [STT billing feature IDs restructured, Pulse Pro pricing live](https://docs.smallest.ai/changelog/voice-agents/2026/5/28.md): Billing feature IDs for Pulse and Pulse Pro have been restructured to namespace by model and transport.
- [Default voice activity detection - `releaseTimeInSeconds` tuned for cleaner turn handoff](https://docs.smallest.ai/changelog/voice-agents/2026/5/25.md): The default `releaseTimeInSeconds` for the voice activity detector has been retuned. New agents pick it up automatically; existing agents are unchanged unless you re-save the config.
- [Agent config screen - redesigned layout](https://docs.smallest.ai/changelog/voice-agents/2026/5/22.md): The agent configuration screen has been redesigned for clarity and faster editing - grouped panels, inline help, and validation closer to where you type.
- [Agent SDK - `agent_log` and `agent_error` events are now persisted and visible on call detail](https://docs.smallest.ai/changelog/voice-agents/2026/5/20.md): Custom logs and structured errors emitted from your agent during a call now persist end-to-end and render on the call detail page in the Atoms console.
- [Pro voices in the agent voice picker - 39 voices across American, British, and Indian accents](https://docs.smallest.ai/changelog/voice-agents/2026/5/15.md): The agent voice picker now has a Pro filter chip alongside V3.1 / Others.
- [Atoms webhooks - full 3-event field reference now in docs](https://docs.smallest.ai/changelog/voice-agents/2026/5/10.md): The Atoms webhooks documentation now contains the full field-level schema for all three lifecycle events: pre-conversation, post-conversation, and.
- [Agent draft-config - 14 missing fields documented + synthesizer `sampleRate`](https://docs.smallest.ai/changelog/voice-agents/2026/5/5.md): The PATCH /atoms/v1/agent/{id}/drafts/{draftId}/config request body now documents the conversation-control, voice-detection, timeout, and pronunciation.
- [Compliance endpoints - phone-number rentals with Plivo identity verification](https://docs.smallest.ai/changelog/voice-agents/2026/5/4.md): Five new endpoints under /atoms/v1/compliance/ document the regulatory-compliance flow for renting phone numbers in countries that require identity.
- [Drop-in mobile voice widgets for iOS, Android, React Native, and Flutter](https://docs.smallest.ai/changelog/voice-agents/2026/4/24.md): Every mobile stack now has a drop-in voice widget.
- [Campaign scheduling, retries, and flat disposition metrics](https://docs.smallest.ai/changelog/voice-agents/2026/4/21.md): POST /campaign now accepts scheduledAt (ISO-8601, must be in the future), maxRetries (0–10, default 3), retryDelay (1–1440 minutes, default 15), and.
- [Agent versioning and post-call metrics](https://docs.smallest.ai/changelog/voice-agents/2026/4/20.md): Every agent now has immutable published versions.