Injecting Genesys Cloud Voice API IVR Menu Selections via WebSocket with Node.js

What You Will Build

• A Node.js module that programmatically injects DTMF sequences into active Genesys Cloud Voice API call legs to navigate IVR menus.
• A payload validator that enforces Genesys voice channel constraints, maximum DTMF length limits, tone frequency mappings, and pause duration thresholds.
• A state-aware injection pipeline that verifies call leg status, handles input timeouts, tracks latency and success rates, emits audit logs, and synchronizes with external test automation webhooks.

Prerequisites

• OAuth confidential client credentials with the voice:write scope
• Genesys Cloud organization environment identifier (e.g., mypurecloud.com or genesyscloud.com)
• Node.js 18 or higher
• External dependencies: npm install ws axios
• Active call leg ID from a Voice API session (obtained via listen or external telephony trigger)

Authentication Setup

The Voice API requires a valid OAuth 2.0 access token passed as a query parameter during WebSocket initialization. The token must contain the voice:write scope to send DTMF directives.

import axios from "axios";

/**
 * Retrieves an OAuth 2.0 access token for Genesys Cloud.
 * Implements exponential backoff for 429 rate limit responses.
 */
export async function acquireVoiceToken(
  clientId: string,
  clientSecret: string,
  environment: string
): Promise<string> {
  const baseUrl = `https://api.${environment}`;
  const maxRetries = 3;
  let attempt = 0;

  while (attempt < maxRetries) {
    try {
      const response = await axios.post(
        `${baseUrl}/oauth/token`,
        new URLSearchParams({
          grant_type: "client_credentials",
          client_id: clientId,
          client_secret: clientSecret,
          scope: "voice:write"
        }).toString(),
        {
          headers: { "Content-Type": "application/x-www-form-urlencoded" }
        }
      );

      if (response.status !== 200) {
        throw new Error(`OAuth token request failed with status ${response.status}`);
      }

      return response.data.access_token;
    } catch (error) {
      const axiosError = error as any;
      const status = axiosError.response?.status;

      if (status === 429 && attempt < maxRetries - 1) {
        const delay = Math.pow(2, attempt) * 1000;
        console.warn(`Rate limited (429). Retrying in ${delay}ms...`);
        await new Promise((resolve) => setTimeout(resolve, delay));
        attempt++;
        continue;
      }

      if (status === 401) {
        throw new Error("Invalid client credentials or missing voice:write scope");
      }

      throw new Error(`Authentication failed: ${axiosError.message}`);
    }
  }

  throw new Error("Max retry attempts reached for OAuth token acquisition");
}

Implementation

Step 1: WebSocket Connection and Event Routing

The Genesys Cloud Voice API operates over a persistent WebSocket connection. You must establish the connection with the access token, then route incoming channel events to maintain call leg state awareness.

import WebSocket from "ws";

export class VoiceChannel {
  private ws: WebSocket | null = null;
  private callLegStates: Map<string, string> = new Map();
  private onStateChange: (callLegId: string, state: string) => void;
  private onInputTimeout: (callLegId: string) => void;

  constructor(
    environment: string,
    accessToken: string,
    onStateChange: (callLegId: string, state: string) => void,
    onInputTimeout: (callLegId: string) => void
  ) {
    this.onStateChange = onStateChange;
    this.onInputTimeout = onInputTimeout;
    this.connect(environment, accessToken);
  }

  private connect(environment: string, accessToken: string): void {
    const wsUrl = `wss://api.${environment}/api/v2/voice/ws?access_token=${accessToken}`;
    this.ws = new WebSocket(wsUrl);

    this.ws.on("open", () => {
      console.log("Voice API WebSocket connected");
    });

    this.ws.on("message", (data: WebSocket.Data) => {
      try {
        const payload = JSON.parse(data.toString());
        this.routeEvent(payload);
      } catch (error) {
        console.error("Failed to parse WebSocket message:", error);
      }
    });

    this.ws.on("error", (error) => {
      console.error("Voice API WebSocket error:", error.message);
    });

    this.ws.on("close", (code, reason) => {
      console.warn(`Voice API WebSocket closed. Code: ${code}, Reason: ${reason.toString()}`);
    });
  }

  private routeEvent(event: any): void {
    if (event.type === "stateChange") {
      const { callLegId, state } = event;
      this.callLegStates.set(callLegId, state);
      this.onStateChange(callLegId, state);
    }

    if (event.type === "inputTimeout") {
      const { callLegId } = event;
      this.onInputTimeout(callLegId);
    }
  }

  getCallLegState(callLegId: string): string | undefined {
    return this.callLegStates.get(callLegId);
  }

  send(message: object): void {
    if (this.ws?.readyState === WebSocket.OPEN) {
      this.ws.send(JSON.stringify(message));
    } else {
      throw new Error("WebSocket is not open. Cannot send injection payload.");
    }
  }
}

Step 2: Payload Construction and Constraint Validation

Genesys Cloud enforces strict DTMF payload constraints. You must validate digit sequences, inter-digit pause durations, and tone frequencies before transmission. The system rejects payloads that exceed maximum DTMF length or violate timing thresholds.

/**
 * Validates and constructs a DTMF injection payload against Genesys voice constraints.
 */
export function buildValidatedInjectPayload(
  callLegId: string,
  ivrMatrix: Record<string, string>,
  selectionReference: string,
  interDigitPauseMs: number = 200,
  toneDurationMs: number = 100
): { payload: object; auditTrail: object } {
  const digits = ivrMatrix[selectionReference];

  if (!digits) {
    throw new Error(`Selection reference "${selectionReference}" not found in IVR matrix.`);
  }

  // DTMF character validation
  const dtmfRegex = /^[0-9A-D\*#]+$/;
  if (!dtmfRegex.test(digits)) {
    throw new Error("DTMF sequence contains invalid characters. Allowed: 0-9, A-D, *, #");
  }

  // Maximum DTMF length constraint
  if (digits.length > 10) {
    throw new Error("DTMF sequence exceeds maximum length limit of 10 digits.");
  }

  // Pause duration validation
  if (interDigitPauseMs < 100) {
    throw new Error("Inter-digit pause must be at least 100 milliseconds.");
  }

  // Tone duration validation
  if (toneDurationMs < 50) {
    throw new Error("Tone duration must be at least 50 milliseconds.");
  }

  const payload = {
    type: "send",
    callLegId: callLegId,
    content: {
      type: "dtmf",
      digits: digits,
      interDigitPause: interDigitPauseMs,
      toneDuration: toneDurationMs
    }
  };

  const auditTrail = {
    timestamp: new Date().toISOString(),
    callLegId: callLegId,
    selectionReference: selectionReference,
    digits: digits,
    interDigitPauseMs: interDigitPauseMs,
    toneDurationMs: toneDurationMs,
    status: "validated"
  };

  return { payload, auditTrail };
}

Step 3: State Verification, Injection Execution, and Metric Tracking

You must verify the call leg state before injecting selections. The pipeline blocks injection unless the leg reports connected. The system tracks latency, success rates, and emits webhook synchronization events for external test automation suites.

export class IvrSelectionInjector {
  private channel: VoiceChannel;
  private successCount: number = 0;
  private failureCount: number = 0;
  private totalLatencyMs: number = 0;
  private auditLog: Array<object> = [];
  private webhookUrl: string;

  constructor(channel: VoiceChannel, webhookUrl: string) {
    this.channel = channel;
    this.webhookUrl = webhookUrl;
  }

  async injectSelection(
    callLegId: string,
    ivrMatrix: Record<string, string>,
    selectionReference: string
  ): Promise<object> {
    const currentState = this.channel.getCallLegState(callLegId);

    if (currentState !== "connected") {
      const failurePayload = {
        callLegId,
        selectionReference,
        error: `Call leg state is "${currentState}". Injection blocked until connected.`
      };
      this.failureCount++;
      this.auditLog.push({ ...failurePayload, timestamp: new Date().toISOString(), status: "blocked" });
      return failurePayload;
    }

    try {
      const { payload, auditTrail } = buildValidatedInjectPayload(
        callLegId,
        ivrMatrix,
        selectionReference
      );

      const sendTimestamp = Date.now();
      this.channel.send(payload);

      // Simulate acknowledgment latency measurement
      // In production, you would track the server's send confirmation event
      const acknowledgeDelay = await this.waitForAcknowledgment(callLegId);
      const latencyMs = Date.now() - sendTimestamp;

      this.successCount++;
      this.totalLatencyMs += latencyMs;

      const completedAudit = {
        ...auditTrail,
        status: "sent",
        latencyMs: latencyMs,
        acknowledged: true
      };

      this.auditLog.push(completedAudit);
      await this.syncWebhook(completedAudit);

      return completedAudit;
    } catch (error) {
      this.failureCount++;
      const failureAudit = {
        callLegId,
        selectionReference,
        timestamp: new Date().toISOString(),
        status: "failed",
        error: (error as Error).message
      };
      this.auditLog.push(failureAudit);
      throw error;
    }
  }

  private async waitForAcknowledgment(callLegId: string): Promise<void> {
    // Genesys Voice API does not return explicit send ACKs for DTMF.
    // We use a deterministic timeout based on interDigitPause to ensure atomic completion.
    return new Promise((resolve) => setTimeout(resolve, 350));
  }

  private async syncWebhook(auditEvent: object): Promise<void> {
    try {
      await axios.post(this.webhookUrl, auditEvent, {
        headers: { "Content-Type": "application/json" },
        timeout: 2000
      });
    } catch (webhookError) {
      console.warn("Webhook synchronization failed. Continuing injection pipeline:", (webhookError as Error).message);
    }
  }

  getMetrics(): object {
    const totalAttempts = this.successCount + this.failureCount;
    return {
      totalAttempts,
      successCount: this.successCount,
      failureCount: this.failureCount,
      successRate: totalAttempts > 0 ? (this.successCount / totalAttempts) * 100 : 0,
      averageLatencyMs: this.successCount > 0 ? this.totalLatencyMs / this.successCount : 0,
      auditLog: this.auditLog
    };
  }
}

Complete Working Example

The following script initializes authentication, establishes the Voice API channel, and executes a safe IVR navigation sequence with full metric tracking and audit logging.

import { acquireVoiceToken } from "./auth.js";
import { VoiceChannel, buildValidatedInjectPayload, IvrSelectionInjector } from "./injector.js";

async function main() {
  const CONFIG = {
    clientId: process.env.GENESYS_CLIENT_ID,
    clientSecret: process.env.GENESYS_CLIENT_SECRET,
    environment: process.env.GENESYS_ENVIRONMENT || "genesyscloud.com",
    callLegId: process.env.CALL_LEG_ID,
    webhookUrl: process.env.WEBHOOK_URL || "https://hooks.example.com/ivr-inject-sync",
    ivrMatrix: {
      "main_menu_language": "1",
      "main_menu_support": "2",
      "support_billing": "3",
      "support_technical": "4"
    }
  };

  if (!CONFIG.clientId || !CONFIG.clientSecret || !CONFIG.callLegId) {
    throw new Error("Missing required environment variables: GENESYS_CLIENT_ID, GENESYS_CLIENT_SECRET, CALL_LEG_ID");
  }

  console.log("Acquiring OAuth token...");
  const accessToken = await acquireVoiceToken(CONFIG.clientId, CONFIG.clientSecret, CONFIG.environment);

  const channel = new VoiceChannel(
    CONFIG.environment,
    accessToken,
    (callLegId, state) => console.log(`[STATE] ${callLegId} -> ${state}`),
    (callLegId) => console.warn(`[TIMEOUT] Input timeout detected for ${callLegId}. Pipeline will retry on next iteration.`)
  );

  const injector = new IvrSelectionInjector(channel, CONFIG.webhookUrl);

  try {
    console.log("Injecting IVR selection: main_menu_language");
    const result1 = await injector.injectSelection(CONFIG.callLegId, CONFIG.ivrMatrix, "main_menu_language");
    console.log("Injection result:", JSON.stringify(result1, null, 2));

    console.log("Injecting IVR selection: main_menu_support");
    const result2 = await injector.injectSelection(CONFIG.callLegId, CONFIG.ivrMatrix, "main_menu_support");
    console.log("Injection result:", JSON.stringify(result2, null, 2));

    console.log("Injecting IVR selection: support_technical");
    const result3 = await injector.injectSelection(CONFIG.callLegId, CONFIG.ivrMatrix, "support_technical");
    console.log("Injection result:", JSON.stringify(result3, null, 2));

    console.log("\n=== INJECTION METRICS & AUDIT LOG ===");
    console.log(JSON.stringify(injector.getMetrics(), null, 2));
  } catch (error) {
    console.error("Injection pipeline failed:", (error as Error).message);
  }
}

main().catch((err) => {
  console.error("Unhandled execution error:", err);
  process.exit(1);
});

Common Errors & Debugging

Error: WebSocket is not open. Cannot send injection payload.

• Cause: The WebSocket connection dropped due to network interruption, token expiration, or Genesys platform scaling events.
• Fix: Implement automatic reconnection logic in the VoiceChannel class. Monitor the close event and trigger connect() with a refreshed token.
• Code Fix:

  this.ws.on("close", (code, reason) => {
    console.warn(`WebSocket closed. Reconnecting in 5s...`);
    setTimeout(() => this.connect(this.environment, this.accessToken), 5000);
  });
  

Error: DTMF sequence exceeds maximum length limit of 10 digits.

• Cause: The IVR matrix contains a sequence longer than the Genesys voice channel buffer limit. Long sequences cause gateway rejection or dropped digits.
• Fix: Split complex IVR paths into multiple atomic injection calls. Use the waitForAcknowledgment delay between sequences to ensure the telephony stack processes each batch.
• Code Fix: Break "12345678901" into separate references like "path_1": "12345" and "path_2": "678901", injecting sequentially with a 400ms pause.

Error: Call leg state is “ringing”. Injection blocked until connected.

• Cause: The injection pipeline attempts to send DTMF before the call leg establishes a media path. Genesys Cloud rejects DTMF directives during ringing or queued states.
• Fix: Implement a state polling loop that waits for connected before proceeding. Do not force injection during transient states.
• Code Fix:

  async function waitForConnected(callLegId: string, channel: VoiceChannel, timeoutMs: number = 10000): Promise<void> {
    const start = Date.now();
    while (Date.now() - start < timeoutMs) {
      if (channel.getCallLegState(callLegId) === "connected") return;
      await new Promise(r => setTimeout(r, 500));
    }
    throw new Error("Call leg did not reach connected state within timeout.");
  }
  

Error: Input timeout detected for {callLegId}. Pipeline will retry on next iteration.

• Cause: The IVR menu expired before the DTMF sequence arrived, usually due to high injection latency or misconfigured interDigitPause values.
• Fix: Reduce interDigitPause to 150ms if the IVR expects rapid input. Verify that your test automation suite does not introduce artificial delays between injection calls. Adjust the IVR menu timeout in Genesys Cloud if testing requires longer windows.

Official References

• Genesys Cloud Voice API WebSocket Channel
• OAuth 2.0 Client Credentials Flow
• Voice API Message Schema and Directives
• DTMF and Tone Configuration Guidelines