Amazon Nova 2 Sonic / Nova 2.5 Sonic (Bedrock)

Overview

Best for: AWS-native contact centers and phone agents (Amazon Connect, Twilio, Vonage) that want low per-token cost and in-Region processing.

At a glance

Transport is HTTP/2 bidirectional streaming. 8 min connection limit. 20 concurrent sessions per account per Region, not adjustable (Nova 2 Sonic). Context 1M for Nova 2 Sonic, 256K for Nova 2.5 Sonic. HIPAA and SOC are Bedrock-level; confirm Nova Sonic in BAA scope. EU via eu-north-1. Telephony via Amazon Connect and partners.

Features

• turn detection with endpointingSensitivity HIGH / MEDIUM / LOW
• barge-in handling without losing context
• function calling with asynchronous tool handling (agent keeps talking while tools run)
• cross-modal input: text messages during a voice session
• conversation history injection at session start
• RAG via your own tools (Bedrock Knowledge Bases integration patterns)
• telephony via Amazon Connect, Twilio, Vonage, AudioCodes; LiveKit and Pipecat integrations
• Strands Bidi Agents (GA Oct 2026) handles reconnects across the 8 minute limit

Pricing

Free tier: None specific to Nova Sonic (AWS Free Tier credits may apply to new accounts).

Source: pricing.us-east-1.amazonaws.com

Setup

1. Create an AWS account and pick a supported Region (e.g. us-east-1).
2. In the Bedrock console confirm access to Amazon Nova 2 Sonic or Nova 2.5 Sonic (and accept any model terms).
3. Create IAM credentials with bedrock:InvokeModelWithBidirectionalStream, or a Bedrock API key (AWS_BEARER_TOKEN_BEDROCK) for quick tests.
4. Use an SDK with HTTP/2 bidirectional streaming support (AWS SDK for JavaScript v3 with NodeHttp2Handler, Python aws_sdk_bedrock_runtime, Java, .NET); boto3 does not stream bidirectionally.
5. Send sessionStart, promptStart, system prompt content, then a long-lived AUDIO content block of audioInput events; read audioOutput, textOutput, toolUse and usageEvent events.
6. Plan reconnects before 8 minutes and request no more than 20 concurrent sessions per Region per account (use more accounts/Regions or Amazon Connect for scale).

Endpoint

https://bedrock-runtime.{region}.amazonaws.com (InvokeModelWithBidirectionalStream over HTTP/2), modelId amazon.nova-2-sonic-v1:0 or amazon.nova-2-5-sonic

Authentication

AWS SigV4 with IAM credentials (or a Bedrock API key). There is no browser token flow: run the stream on your backend and relay audio from the browser or phone over WebSocket/WebRTC.

import { BedrockRuntimeClient, InvokeModelWithBidirectionalStreamCommand } from "@aws-sdk/client-bedrock-runtime";
import { NodeHttp2Handler } from "@smithy/node-http-handler";
import { randomUUID } from "node:crypto";

const client = new BedrockRuntimeClient({ region: "us-east-1", requestHandler: new NodeHttp2Handler({ requestTimeout: 300000 }) });
const P = randomUUID(), SYS = randomUUID(), MIC = randomUUID();
const enc = (event) => ({ chunk: { bytes: new TextEncoder().encode(JSON.stringify({ event })) } });
const audioCfg = { mediaType: "audio/lpcm", sampleRateHertz: 16000, sampleSizeBits: 16, channelCount: 1, audioType: "SPEECH", encoding: "base64" };

async function* input(micChunks) {
  yield enc({ sessionStart: { inferenceConfiguration: { maxTokens: 1024, topP: 0.9, temperature: 0.7 }, turnDetectionConfiguration: { endpointingSensitivity: "MEDIUM" } } });
  yield enc({ promptStart: { promptName: P, textOutputConfiguration: { mediaType: "text/plain" },
    audioOutputConfiguration: { ...audioCfg, sampleRateHertz: 24000, voiceId: "matthew" } } });
  yield enc({ contentStart: { promptName: P, contentName: SYS, type: "TEXT", interactive: false, role: "SYSTEM", textInputConfiguration: { mediaType: "text/plain" } } });
  yield enc({ textInput: { promptName: P, contentName: SYS, content: "You are a friendly support agent. Keep answers short." } });
  yield enc({ contentEnd: { promptName: P, contentName: SYS } });
  yield enc({ contentStart: { promptName: P, contentName: MIC, type: "AUDIO", interactive: true, role: "USER", audioInputConfiguration: audioCfg } });
  for await (const pcm of micChunks()) // 16 kHz mono PCM16, ~32 ms frames, streamed in real time
    yield enc({ audioInput: { promptName: P, contentName: MIC, content: Buffer.from(pcm).toString("base64") } });
  yield enc({ contentEnd: { promptName: P, contentName: MIC } });
  yield enc({ promptEnd: { promptName: P } });
  yield enc({ sessionEnd: {} });
}

export async function talk(micChunks, play) {
  const res = await client.send(new InvokeModelWithBidirectionalStreamCommand({ modelId: "amazon.nova-2-sonic-v1:0", body: input(micChunks) }));
  for await (const ev of res.body) {
    if (!ev.chunk?.bytes) continue;
    const msg = JSON.parse(new TextDecoder().decode(ev.chunk.bytes)).event;
    if (msg?.audioOutput) play(Buffer.from(msg.audioOutput.content, "base64")); // 24 kHz PCM16
  }
}

Written from the current docs. Check the vendor's SDK version before you ship.

Warnings

Plus 14 warnings that apply to all voice-to-voice APIs. See category warnings.

Limits

• Connection limit 8 minutes; renew the connection and carry history forward (AWS samples and Strands Bidi Agents do this)
• Default quota 20 concurrent InvokeModelWithBidirectionalStream sessions per account per Region for Nova 2 Sonic, documented as not adjustable
• Context window: Nova 2 Sonic 1M tokens (64K output); Nova 2.5 Sonic 256K per launch post
• Conversation history can only be injected once, after the system prompt and before audio streaming
• In-Region inference only (no geo or global cross-region profiles)
• Standard service tier only (no Priority, Flex or Reserved)

Models and products

Docs and sources

Docs

• Nova 2 Sonic user guide
• Input events reference
• Bedrock model card
• Release notes
• Samples
• Bedrock pricing

Sources used

• pricing.us-east-1.amazonaws.com/offers/v1.0/aws/AmazonBedrock/current/us-east-1...
• docs.aws.amazon.com/bedrock/latest/userguide/model-card-amazon-nova-2-sonic.html
• docs.aws.amazon.com/nova/latest/nova2-userguide/using-conversational-speech.html
• docs.aws.amazon.com/nova/latest/nova2-userguide/sonic-input-events.html
• docs.aws.amazon.com/nova/latest/nova2-userguide/release-notes.md
• aws.amazon.com/about-aws/whats-new/2026/10/amazon-nova-2.5-sonic/
• aws.amazon.com/blogs/aws/introducing-amazon-nova-2-sonic-next-generation-speech...
• strandsagents.com/blog/bidi-agents-now-ga/
• repost.aws/questions/QUNhHJ1dstS9mzzE6ZyRepjg/how-long-a-sonic-token-is