Gemini 3.1 Flash Live (April 2026): Google's Voice Agent Model in Production

Google launched Gemini 3.1 Flash Live in April 2026 with native audio, 30 HD voices, 24 languages, and a Vertex AI Live API. Here is the production take.

What changed

flowchart LR
  User --> Edge[Cloudflare Edge]
  Edge --> WS[(WebSocket Bridge)]
  WS --> LLM[OpenAI Realtime gpt-4o]
  LLM --> Tool[Tool Call]
  Tool --> CRM[(CRM API)]
  Tool --> EHR[(EHR API)]
  LLM --> User

Google rolled out Gemini 3.1 Flash Live in April 2026 as the successor to the older gemini-live-2.5-flash-preview-native-audio-09-2025 model (which is being deprecated and removed on March 19 2026 — migrate to gemini-live-2.5-flash-native-audio or the new 3.1 line).

The 3.1 Flash Live release brings:

• Lower latency for first-token and audio-out
• 30 HD voices across 24 languages in native audio mode
• Improved instruction-following for tool-use and complex multi-turn workflows
• Gemini Live API on Vertex AI with enterprise-grade controls (private VPC, regional residency, audit logging)

Google's framing — published on the official Google blog — positions Gemini 3.1 Flash Live as the right model for "real-time conversational agents" specifically, separating it from the broader Gemini 3 family used for text and reasoning.

The Vertex AI Live API release matters separately: it brings the Live API into the same governance plane as the rest of Vertex (IAM, VPC Service Controls, customer-managed keys), which is what was blocking many regulated-industry adoptions.

Why it matters for voice agent builders

Gemini Live is now a credible third option alongside OpenAI Realtime and the Anthropic ecosystem (Claude does not yet ship a native realtime audio model — you build with STT + LLM + TTS).

Three concrete implications:

1. Multilingual is finally first-class. 24 languages with native audio means you do not need a separate TTS for Hindi, Korean, or Portuguese — the same model output is conversational in all of them.
2. Vertex AI is now a real play for enterprise voice. Private VPC, customer-managed keys, and regional residency unlock financial services, healthcare, and EU public-sector deployments.
3. Google's audio benchmark numbers close the gap. On internal eval suites, Gemini 3.1 Flash Live trades blows with gpt-realtime on naturalness and beats it on multilingual NLU.

How CallSphere applies this

CallSphere uses Gemini Live in two scenarios. Multilingual outbound for India-region pilots runs through Gemini 3.1 Flash Live because the model handles Hindi-English code-switching with less prompt engineering than OpenAI Realtime. Healthcare deployments in EU regions route through Vertex AI Live in the europe-west4 zone because we need EU data residency for some pilots.

The flexibility comes from the architecture: across CallSphere's 6 verticals, 37 agents, 90+ tools, and 115+ DB tables, the LLM and TTS choice is per-agent. The Healthcare Voice Agent (FastAPI :8084, 14 tools, sentiment –1.0 to 1.0 + lead score 0-100) defaults to OpenAI Realtime; OneRoof Real Estate (10 specialist agents) defaults to OpenAI Agents SDK + WebRTC; Salon GlamBook (4 agents) defaults to ElevenLabs; and our multilingual or EU-resident customers default to Gemini Live. Same dashboard, same $49 / $99 / $149 pricing tiers.

Build and migration steps

1. Audit deprecation: anything on gemini-live-2.5-flash-preview-native-audio-09-2025 must move before March 19 2026.
2. For new builds, start with gemini-3.1-flash-live in AI Studio and test naturalness on your top 10 prompts.
3. For enterprise/regulated builds, provision the Vertex AI Live API in the right region with VPC-SC and CMEK enabled.
4. Map your tool definitions — Gemini's function-calling format is not identical to OpenAI's; expect a small adapter layer.
5. Re-tune VAD silence thresholds — Gemini 3.1 has different turn-end behavior than 2.5.
6. Run a multilingual eval if that matters to you — Gemini's gap over gpt-realtime is widest on non-English locales.
7. Watch quotas — Vertex Live regional capacity is still expanding; pre-reserve if your fleet is large.

FAQ

When was Gemini 3.1 Flash Live released? April 2026, via the official Google blog and Google AI Studio. The Vertex AI Live API became GA around the same time.

How many languages does Gemini Live support? The native audio API supports 24 languages with 30 HD voices. Code-switching is supported within a session.

Is the older Gemini Live model being deprecated? Yes. gemini-live-2.5-flash-preview-native-audio-09-2025 is removed on March 19 2026. Migrate to gemini-live-2.5-flash-native-audio or to the 3.1 line.

Can I use Gemini Live for HIPAA workloads? Via Vertex AI with a Business Associate Agreement, yes. Google provides BAA terms on Vertex enterprise tiers.

How does Gemini 3.1 Flash Live compare to OpenAI gpt-realtime? On English naturalness it is close to a tie. On multilingual breadth Gemini wins. On developer ecosystem and tooling OpenAI leads. CallSphere uses both depending on customer requirements.

Sources

• Google blog — "Gemini 3.1 Flash Live: Google's latest AI audio model" — https://blog.google/innovation-and-ai/models-and-research/gemini-models/gemini-3-1-flash-live/
• Google blog — "Build real-time conversational agents with Gemini 3.1 Flash Live" — https://blog.google/innovation-and-ai/technology/developers-tools/build-with-gemini-3-1-flash-live/
• Google Cloud blog — "Gemini Live API available on Vertex AI" — https://cloud.google.com/blog/products/ai-machine-learning/gemini-live-api-available-on-vertex-ai
• Gemini API release notes — https://ai.google.dev/gemini-api/docs/changelog