Executing NICE CXone Predictive Dialer Call Simulation Tests via REST API with Go

What You Will Build

• A Go module that constructs, validates, and dispatches predictive dialer simulation payloads to NICE CXone, tracks execution states, enforces concurrency limits, and routes webhook events to external QA monitors.
• This tutorial uses the NICE CXone Dialer and Simulation REST APIs with OAuth 2.0 client credentials authentication.
• The implementation is written in Go 1.21 using only the standard library for maximum portability and zero external dependencies.

Prerequisites

• A NICE CXone organization with a configured OAuth 2.0 confidential client application.
• Required OAuth scopes: dialer:campaigns:write dialer:simulations:write dialer:simulations:read dialer:metrics:read.
• Go runtime version 1.21 or higher.
• Network access to your CXone API gateway (https://{orgId}.api.nicecxone.com).
• A valid campaign ID and virtual agent flow ID configured in your CXone organization.

Authentication Setup

CXone uses standard OAuth 2.0 client credentials flow for server-to-server automation. The token manager below caches the access token and refreshes it automatically when the expiration window approaches. This prevents unnecessary authentication requests and reduces latency during simulation dispatch.

package main

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"sync"
	"time"
)

// TokenResponse represents the CXone OAuth token payload.
type TokenResponse struct {
	AccessToken string `json:"access_token"`
	TokenType   string `json:"token_type"`
	ExpiresIn   int    `json:"expires_in"`
	Scope       string `json:"scope"`
}

// AuthManager handles OAuth token retrieval and caching.
type AuthManager struct {
	orgID       string
	clientID    string
	clientSecret string
	scope       string
	token       *TokenResponse
	mu          sync.RWMutex
	expiry      time.Time
	httpClient  *http.Client
}

// NewAuthManager initializes the authentication handler.
func NewAuthManager(orgID, clientID, clientSecret, scope string) *AuthManager {
	return &AuthManager{
		orgID:        orgID,
		clientID:     clientID,
		clientSecret: clientSecret,
		scope:        scope,
		httpClient:   &http.Client{Timeout: 10 * time.Second},
	}
}

// GetToken returns a valid access token, refreshing automatically if expired.
func (a *AuthManager) GetToken(ctx context.Context) (string, error) {
	a.mu.RLock()
	if a.token != nil && time.Now().Before(a.expiry.Add(-30*time.Second)) {
		token := a.token.AccessToken
		a.mu.RUnlock()
		return token, nil
	}
	a.mu.RUnlock()

	a.mu.Lock()
	defer a.mu.Unlock()

	// Double-check after acquiring write lock
	if a.token != nil && time.Now().Before(a.expiry.Add(-30*time.Second)) {
		return a.token.AccessToken, nil
	}

	payload := fmt.Sprintf("grant_type=client_credentials&scope=%s", a.scope)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, 
		fmt.Sprintf("https://%s.api.nicecxone.com/oauth/token", a.orgID), 
		bytes.NewBufferString(payload))
	if err != nil {
		return "", fmt.Errorf("failed to create auth request: %w", err)
	}

	req.SetBasicAuth(a.clientID, a.clientSecret)
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")

	resp, err := a.httpClient.Do(req)
	if err != nil {
		return "", fmt.Errorf("authentication request failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("oauth error: status %d", resp.StatusCode)
	}

	var tokenResp TokenResponse
	if err := json.NewDecoder(resp.Body).Decode(&tokenResp); err != nil {
		return "", fmt.Errorf("failed to decode token response: %w", err)
	}

	a.token = &tokenResp
	a.expiry = time.Now().Add(time.Duration(tokenResp.ExpiresIn) * time.Second)
	return tokenResp.AccessToken, nil
}

Implementation

Step 1: Payload Construction and Schema Validation

CXone enforces strict schema validation for simulation jobs. The payload must contain a valid campaign identifier, virtual agent matrix directives, outcome injection probabilities that sum to one or less, and concurrency limits that respect organizational constraints. The validation function below checks these constraints before dispatch to prevent 422 Unprocessable Entity responses.

import (
	"encoding/json"
	"fmt"
	"regexp"
	"strings"
)

// VirtualAgentMatrix defines VA routing directives for the simulation.
type VirtualAgentMatrix struct {
	FlowID   string `json:"flowId,omitempty"`
	ScriptID string `json:"scriptId,omitempty"`
	Language string `json:"language,omitempty"`
}

// OutcomeInjection configures simulated call results.
type OutcomeInjection struct {
	Enabled                bool    `json:"enabled"`
	DialToneProbability    float64 `json:"dialToneProbability,omitempty"`
	BusySignalProbability  float64 `json:"busySignalProbability,omitempty"`
	NoAnswerProbability    float64 `json:"noAnswerProbability,omitempty"`
	AnswerProbability      float64 `json:"answerProbability,omitempty"`
}

// SimulationPayload matches the CXone /api/v2/dialer/simulations schema.
type SimulationPayload struct {
	CampaignID         string               `json:"campaignId"`
	VirtualAgentMatrix VirtualAgentMatrix   `json:"virtualAgentMatrix"`
	OutcomeInjection   OutcomeInjection     `json:"outcomeInjection"`
	ConcurrencyLimit   int                  `json:"concurrencyLimit"`
	MaxCalls           int                  `json:"maxCalls"`
	ComplianceBypass   bool                 `json:"complianceBypass"`
	WebhookURL         string               `json:"webhookUrl,omitempty"`
	Tag                string               `json:"tag,omitempty"`
}

// ValidatePayload enforces CXone dialer testing constraints.
func ValidatePayload(p SimulationPayload, maxConcurrent int) error {
	// Campaign ID must match CXone UUID format
	campaignRegex := regexp.MustCompile(`^[a-f0-9-]{36}$`)
	if !campaignRegex.MatchString(p.CampaignID) {
		return fmt.Errorf("invalid campaign ID format: %s", p.CampaignID)
	}

	// Virtual agent matrix requires at least one routing directive
	if p.VirtualAgentMatrix.FlowID == "" && p.VirtualAgentMatrix.ScriptID == "" {
		return fmt.Errorf("virtualAgentMatrix requires flowId or scriptId")
	}

	// Outcome injection probabilities must not exceed 1.0
	totalProb := p.OutcomeInjection.DialToneProbability +
		p.OutcomeInjection.BusySignalProbability +
		p.OutcomeInjection.NoAnswerProbability +
		p.OutcomeInjection.AnswerProbability
	if totalProb > 1.0 {
		return fmt.Errorf("outcome injection probabilities sum to %.2f, must be <= 1.0", totalProb)
	}

	// Concurrency limit must respect organizational maximum
	if p.ConcurrencyLimit > maxConcurrent || p.ConcurrencyLimit < 1 {
		return fmt.Errorf("concurrencyLimit %d exceeds maximum %d or is below minimum 1", p.ConcurrencyLimit, maxConcurrent)
	}

	// Compliance bypass must be explicitly declared
	if !p.ComplianceBypass {
		return fmt.Errorf("complianceBypass must be true for simulation execution")
	}

	return nil
}

Step 2: Atomic POST Dispatch with Format Verification

CXone requires atomic simulation creation. The dispatch function serializes the validated payload, verifies the JSON format matches the expected schema, and executes the POST request. The implementation includes automatic retry logic for 429 Too Many Requests responses using exponential backoff. This prevents rate-limit cascades during high-frequency testing.

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"time"
)

// SimulationResponse represents the CXone simulation creation response.
type SimulationResponse struct {
	ID    string `json:"id"`
	State string `json:"state"`
	Error string `json:"error,omitempty"`
}

// DispatchSimulation sends the payload to CXone with retry logic for 429 responses.
func DispatchSimulation(ctx context.Context, auth *AuthManager, payload SimulationPayload, maxRetries int) (*SimulationResponse, error) {
	token, err := auth.GetToken(ctx)
	if err != nil {
		return nil, fmt.Errorf("authentication failed: %w", err)
	}

	jsonData, err := json.Marshal(payload)
	if err != nil {
		return nil, fmt.Errorf("payload serialization failed: %w", err)
	}

	// Format verification: ensure JSON is valid and contains required fields
	var verified map[string]interface{}
	if err := json.Unmarshal(jsonData, &verified); err != nil {
		return nil, fmt.Errorf("format verification failed: %w", err)
	}
	if _, exists := verified["campaignId"]; !exists {
		return nil, fmt.Errorf("format verification failed: missing campaignId")
	}

	url := fmt.Sprintf("https://%s.api.nicecxone.com/api/v2/dialer/simulations", auth.orgID)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(jsonData))
	if err != nil {
		return nil, fmt.Errorf("request creation failed: %w", err)
	}

	req.Header.Set("Authorization", "Bearer "+token)
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json")

	var resp *http.Response
	var body []byte
	for attempt := 0; attempt <= maxRetries; attempt++ {
		resp, err = auth.httpClient.Do(req)
		if err != nil {
			return nil, fmt.Errorf("dispatch request failed: %w", err)
		}

		body, err = io.ReadAll(resp.Body)
		resp.Body.Close()
		if err != nil {
			return nil, fmt.Errorf("response read failed: %w", err)
		}

		if resp.StatusCode == http.StatusTooManyRequests {
			if attempt == maxRetries {
				return nil, fmt.Errorf("max retries reached for 429 response")
			}
			backoff := time.Duration(1<<uint(attempt)) * time.Second
			time.Sleep(backoff)
			continue
		}

		if resp.StatusCode != http.StatusCreated {
			return nil, fmt.Errorf("dispatch failed with status %d: %s", resp.StatusCode, string(body))
		}

		break
	}

	var simResp SimulationResponse
	if err := json.Unmarshal(body, &simResp); err != nil {
		return nil, fmt.Errorf("response parsing failed: %w", err)
	}

	return &simResp, nil
}

Step 3: Execution Validation and Call State Verification

After dispatch, CXone transitions the simulation through multiple states. The validation logic polls the simulation endpoint, verifies call state progression, and checks compliance rule bypass execution. This prevents false metric reporting by ensuring the simulation actually executed before aggregating results.

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"time"
)

// SimulationStatus represents the execution state from CXone.
type SimulationStatus struct {
	ID             string `json:"id"`
	State          string `json:"state"`
	CallsAttempted int    `json:"callsAttempted"`
	CallsCompleted int    `json:"callsCompleted"`
	ComplianceBypassed bool `json:"complianceBypassed"`
	Errors         []struct {
		Code    string `json:"code"`
		Message string `json:"message"`
	} `json:"errors,omitempty"`
}

// TrackExecution polls simulation status until completion or failure.
func TrackExecution(ctx context.Context, auth *AuthManager, simulationID string, pollInterval, timeout time.Duration) (*SimulationStatus, error) {
	url := fmt.Sprintf("https://%s.api.nicecxone.com/api/v2/dialer/simulations/%s", auth.orgID, simulationID)
	startTime := time.Now()

	for {
		select {
		case <-ctx.Done():
			return nil, fmt.Errorf("execution tracking cancelled: %w", ctx.Err())
		case <-time.After(timeout):
			return nil, fmt.Errorf("execution tracking timed out after %v", timeout)
		default:
			token, err := auth.GetToken(ctx)
			if err != nil {
				return nil, fmt.Errorf("token refresh failed during tracking: %w", err)
			}

			req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
			if err != nil {
				return nil, fmt.Errorf("status request creation failed: %w", err)
			}
			req.Header.Set("Authorization", "Bearer "+token)
			req.Header.Set("Accept", "application/json")

			resp, err := auth.httpClient.Do(req)
			if err != nil {
				return nil, fmt.Errorf("status request failed: %w", err)
			}

			body, err := io.ReadAll(resp.Body)
			resp.Body.Close()
			if err != nil {
				return nil, fmt.Errorf("status response read failed: %w", err)
			}

			if resp.StatusCode != http.StatusOK {
				return nil, fmt.Errorf("status check failed with %d: %s", resp.StatusCode, string(body))
			}

			var status SimulationStatus
			if err := json.Unmarshal(body, &status); err != nil {
				return nil, fmt.Errorf("status parsing failed: %w", err)
			}

			// Verify compliance bypass pipeline execution
			if status.ComplianceBypassed {
				fmt.Printf("Compliance bypass pipeline verified for simulation %s\n", simulationID)
			}

			// Check terminal states
			if status.State == "completed" || status.State == "failed" {
				latency := time.Since(startTime)
				fmt.Printf("Simulation %s finished in %v. State: %s\n", simulationID, latency, status.State)
				return &status, nil
			}

			time.Sleep(pollInterval)
		}
	}
}

Step 4: Webhook Synchronization and Metric Aggregation

CXone pushes real-time simulation events to the configured webhook URL. The receiver below processes these events, synchronizes with external QA monitoring tools, and triggers automatic metric aggregation. The implementation calculates simulation accuracy rates by comparing injected outcomes against actual call states.

import (
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"time"
)

// WebhookEvent represents a CXone simulation callback.
type WebhookEvent struct {
	SimulationID  string `json:"simulationId"`
	CallID        string `json:"callId"`
	State         string `json:"state"`
	Timestamp     string `json:"timestamp"`
	Outcome       string `json:"outcome"`
	DurationMs    int    `json:"durationMs"`
}

// MetricAggregator tracks simulation performance.
type MetricAggregator struct {
	TotalCalls     int
	CompletedCalls int
	TotalLatency   time.Duration
	AccuracyRate   float64
}

// HandleWebhook processes CXone simulation events and updates metrics.
func HandleWebhook(m *MetricAggregator) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}

		var event WebhookEvent
		if err := json.NewDecoder(r.Body).Decode(&event); err != nil {
			http.Error(w, "invalid payload", http.StatusBadRequest)
			return
		}

		m.TotalCalls++
		if event.State == "completed" {
			m.CompletedCalls++
		}

		// Calculate accuracy rate based on expected vs actual outcomes
		expectedOutcomes := map[string]bool{"answered": true, "busy": true, "no-answer": true, "voicemail": true}
		if expectedOutcomes[event.Outcome] {
			m.AccuracyRate = float64(m.CompletedCalls) / float64(m.TotalCalls)
		}

		latency := time.Duration(event.DurationMs) * time.Millisecond
		m.TotalLatency += latency

		log.Printf("Webhook sync: simulation=%s call=%s state=%s outcome=%s latency=%v",
			event.SimulationID, event.CallID, event.State, event.Outcome, latency)

		w.WriteHeader(http.StatusOK)
		fmt.Fprintln(w, `{"status":"received"}`)
	}
}

// TriggerMetricAggregation sends aggregated metrics to CXone for persistent storage.
func TriggerMetricAggregation(ctx context.Context, auth *AuthManager, simulationID string, metrics MetricAggregator) error {
	token, err := auth.GetToken(ctx)
	if err != nil {
		return fmt.Errorf("token retrieval failed: %w", err)
	}

	payload := map[string]interface{}{
		"simulationId": simulationID,
		"metrics": map[string]interface{}{
			"totalCalls":     metrics.TotalCalls,
			"completedCalls": metrics.CompletedCalls,
			"averageLatencyMs": metrics.TotalLatency.Milliseconds() / int64(max(1, metrics.TotalCalls)),
			"accuracyRate":   metrics.AccuracyRate,
		},
	}

	jsonData, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("metric payload serialization failed: %w", err)
	}

	url := fmt.Sprintf("https://%s.api.nicecxone.com/api/v2/dialer/metrics/aggregations", auth.orgID)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(jsonData))
	if err != nil {
		return fmt.Errorf("metric request creation failed: %w", err)
	}

	req.Header.Set("Authorization", "Bearer "+token)
	req.Header.Set("Content-Type", "application/json")

	resp, err := auth.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("metric dispatch failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusAccepted && resp.StatusCode != http.StatusOK {
		return fmt.Errorf("metric aggregation failed with status %d", resp.StatusCode)
	}

	return nil
}

Step 5: Execution Audit Logging and Simulator Executor

Operational compliance requires immutable audit trails. The executor below ties authentication, validation, dispatch, tracking, and metrics together. It writes structured JSON audit logs for every phase of the simulation lifecycle, exposing a clean interface for automated dialer management pipelines.

import (
	"encoding/json"
	"fmt"
	"log"
	"os"
	"time"
)

// AuditEntry records simulation lifecycle events.
type AuditEntry struct {
	Timestamp   string      `json:"timestamp"`
	EventType   string      `json:"eventType"`
	SimulationID string     `json:"simulationId,omitempty"`
	Payload     interface{} `json:"payload,omitempty"`
	Result      string      `json:"result"`
	Error       string      `json:"error,omitempty"`
}

// SimulatorExecutor orchestrates the complete simulation lifecycle.
type SimulatorExecutor struct {
	Auth      *AuthManager
	MaxConcurrent int
	Metrics   MetricAggregator
	AuditLog  *os.File
}

// NewSimulatorExecutor initializes the executor with audit logging.
func NewSimulatorExecutor(auth *AuthManager, maxConcurrent int, logPath string) (*SimulatorExecutor, error) {
	file, err := os.OpenFile(logPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		return nil, fmt.Errorf("audit log initialization failed: %w", err)
	}
	return &SimulatorExecutor{
		Auth:          auth,
		MaxConcurrent: maxConcurrent,
		AuditLog:      file,
	}, nil
}

// WriteAudit logs a structured JSON entry.
func (e *SimulatorExecutor) WriteAudit(eventType string, simID string, payload interface{}, result string, err error) {
	entry := AuditEntry{
		Timestamp:  time.Now().UTC().Format(time.RFC3339),
		EventType:  eventType,
		SimulationID: simID,
		Payload:    payload,
		Result:     result,
	}
	if err != nil {
		entry.Error = err.Error()
	}
	data, _ := json.Marshal(entry)
	fmt.Fprintln(e.AuditLog, string(data))
}

// ExecuteSimulation runs the complete testing pipeline.
func (e *SimulatorExecutor) ExecuteSimulation(ctx context.Context, payload SimulationPayload) error {
	// Phase 1: Validation
	if err := ValidatePayload(payload, e.MaxConcurrent); err != nil {
		e.WriteAudit("validation", "", payload, "failed", err)
		return fmt.Errorf("validation phase failed: %w", err)
	}
	e.WriteAudit("validation", "", payload, "passed", nil)

	// Phase 2: Dispatch
	simResp, err := DispatchSimulation(ctx, e.Auth, payload, 3)
	if err != nil {
		e.WriteAudit("dispatch", "", payload, "failed", err)
		return fmt.Errorf("dispatch phase failed: %w", err)
	}
	e.WriteAudit("dispatch", simResp.ID, payload, "success", nil)

	// Phase 3: Execution Tracking
	status, err := TrackExecution(ctx, e.Auth, simResp.ID, 2*time.Second, 5*time.Minute)
	if err != nil {
		e.WriteAudit("tracking", simResp.ID, nil, "failed", err)
		return fmt.Errorf("tracking phase failed: %w", err)
	}
	e.WriteAudit("tracking", simResp.ID, status, "completed", nil)

	// Phase 4: Metric Aggregation
	if err := TriggerMetricAggregation(ctx, e.Auth, simResp.ID, e.Metrics); err != nil {
		e.WriteAudit("metrics", simResp.ID, nil, "failed", err)
		return fmt.Errorf("metric aggregation failed: %w", err)
	}
	e.WriteAudit("metrics", simResp.ID, e.Metrics, "aggregated", nil)

	return nil
}

Complete Working Example

package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"time"
)

func main() {
	// Configuration
	orgID := os.Getenv("CXONE_ORG_ID")
	clientID := os.Getenv("CXONE_CLIENT_ID")
	clientSecret := os.Getenv("CXONE_CLIENT_SECRET")
	scope := "dialer:campaigns:write dialer:simulations:write dialer:simulations:read dialer:metrics:read"

	if orgID == "" || clientID == "" || clientSecret == "" {
		log.Fatal("CXONE_ORG_ID, CXONE_CLIENT_ID, and CXONE_CLIENT_SECRET environment variables are required")
	}

	// Initialize components
	auth := NewAuthManager(orgID, clientID, clientSecret, scope)
	executor, err := NewSimulatorExecutor(auth, 5, "simulation_audit.log")
	if err != nil {
		log.Fatalf("Executor initialization failed: %v", err)
	}
	defer executor.AuditLog.Close()

	// Start webhook receiver for QA synchronization
	metrics := executor.Metrics
	http.HandleFunc("/webhook/simulation-events", HandleWebhook(&metrics))
	go func() {
		log.Println("Webhook receiver listening on :8080")
		if err := http.ListenAndServe(":8080", nil); err != nil {
			log.Printf("Webhook server error: %v", err)
		}
	}()

	// Construct simulation payload
	payload := SimulationPayload{
		CampaignID: "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
		VirtualAgentMatrix: VirtualAgentMatrix{
			FlowID:   "va-flow-12345",
			ScriptID: "script-qa-001",
			Language: "en-US",
		},
		OutcomeInjection: OutcomeInjection{
			Enabled:               true,
			DialToneProbability:   0.15,
			BusySignalProbability: 0.20,
			NoAnswerProbability:   0.25,
			AnswerProbability:     0.40,
		},
		ConcurrencyLimit:  5,
		MaxCalls:          50,
		ComplianceBypass:  true,
		WebhookURL:        "http://localhost:8080/webhook/simulation-events",
		Tag:               "predictive-calibration-test",
	}

	// Execute simulation pipeline
	ctx := context.Background()
	if err := executor.ExecuteSimulation(ctx, payload); err != nil {
		log.Fatalf("Simulation pipeline failed: %v", err)
	}

	fmt.Println("Simulation execution completed successfully. Audit log written to simulation_audit.log")
}

Common Errors & Debugging

Error: HTTP 401 Unauthorized

• What causes it: The OAuth token has expired or the client credentials are invalid.
• How to fix it: Verify environment variables contain the correct client ID and secret. Ensure the token manager refresh logic is not bypassed. Check that the OAuth client application is enabled in the CXone admin console.
• Code showing the fix: The AuthManager.GetToken method automatically refreshes tokens when expiration approaches. If credentials are wrong, update the environment variables and restart the executor.

Error: HTTP 403 Forbidden

• What causes it: The OAuth client lacks the required scopes for dialer simulation operations.
• How to fix it: Grant dialer:campaigns:write, dialer:simulations:write, dialer:simulations:read, and dialer:metrics:read scopes to the client application in CXone.
• Code showing the fix: Update the scope variable in main() to include all required scopes. CXone validates scope permissions at the API gateway level before routing the request.

Error: HTTP 409 Conflict

• What causes it: The organization has reached the maximum concurrent simulation limit. CXone enforces a hard limit of five active simulations per organization.
• How to fix it: Reduce the ConcurrencyLimit in the payload or wait for existing simulations to complete. Implement a queueing mechanism in your automation pipeline.
• Code showing the fix: The ValidatePayload function checks maxConcurrent before dispatch. Adjust the limit parameter in NewSimulatorExecutor to match your organizational constraints.

Error: HTTP 422 Unprocessable Entity

• What causes it: The payload violates CXone schema constraints. Common causes include invalid campaign ID format, missing virtual agent directives, or outcome probabilities exceeding 1.0.
• How to fix it: Run the payload through ValidatePayload before dispatch. Verify the campaign ID matches UUID format and that at least one virtual agent directive is present.
• Code showing the fix: The validation function returns explicit error messages indicating which constraint failed. Correct the payload fields and retry.

Error: HTTP 429 Too Many Requests

• What causes it: The API gateway rate limit has been exceeded. CXone enforces per-client and per-endpoint rate limits.
• How to fix it: Implement exponential backoff retry logic. The DispatchSimulation function includes automatic retry with increasing delay intervals.
• Code showing the fix: The retry loop in DispatchSimulation catches 429 responses, sleeps for 1<<attempt seconds, and retries up to maxRetries times. Increase maxRetries if your testing volume requires longer backoff windows.

Official References

• NICE CXone OAuth 2.0 Authentication Guide
• NICE CXone Dialer Simulations API
• NICE CXone Dialer Metrics Aggregation API
• Go net/http Package Documentation
• Go context Package Documentation