Sending Proactive Outbound Messages using the Agentless SMS API
What This Guide Covers
You will configure a Genesys Cloud tenant for programmatic outbound SMS, construct production-ready API payloads for immediate message dispatch, and implement delivery status webhooks with dead-letter queue handling. The end result is a resilient, compliance-aware outbound messaging pipeline that integrates with external business systems while maintaining carrier deliverability and conversation threading.
Prerequisites, Roles & Licensing
- Licensing Tier: CX 1, CX 2, or CX 3 with the Messaging Add-on (or CX 3 Enterprise bundle which includes Messaging). Agentless outbound requires active messaging licenses assigned to the organization, not individual agents.
- Permission Strings:
messaging:outbound:view,messaging:outbound:edit,user:manage(for OAuth client provisioning) - OAuth Scopes:
messaging:outbound,oauth:api - External Dependencies:
- Registered 10DLC campaign and Sender ID (US/CA) or Long Code/Short Code provisioning
- Publicly accessible HTTPS endpoint for delivery status webhooks
- External system capable of generating UUIDv4 identifiers and maintaining conversation state
The Implementation Deep-Dive
1. Sender Identity Configuration and Carrier Compliance Gating
Before issuing a single API call, you must establish a trusted sender identity. Mobile network operators enforce strict filtering on outbound SMS. Unregistered or misconfigured sender identities trigger carrier-level blocking, which appears as a failed status in Genesys Cloud without detailed error payloads.
Navigate to Admin > Messaging > Agentless Messaging > Sender Identities. Create a new identity using a verified 10-digit long code (10DLC) or short code. Map the identity to a registered 10DLC campaign. The campaign must include an approved message template or a general use category with content validation enabled.
The Trap: Deploying outbound traffic before completing 10DLC campaign registration and content validation. Carriers will reject messages at the SMPP gateway level. Genesys Cloud returns a 202 Accepted response initially, then transitions the message to failed with a generic carrier_rejected code. You lose visibility into the exact rejection reason, and your sender reputation degrades rapidly.
Architectural Reasoning: We gate outbound traffic behind compliance validation because carrier filtering operates asynchronously. The API layer cannot predict carrier acceptance. By enforcing 10DLC registration and template approval in the tenant configuration, you shift compliance enforcement upstream. This prevents your external systems from accumulating delivery failures and ensures that every 202 Accepted response correlates to a high probability of successful delivery. You also reduce support ticket volume by eliminating ambiguous failure states.
2. API Payload Construction and Conversation State Management
The immediate outbound endpoint expects a structured JSON payload that defines the message content, routing parameters, and conversation state. You will use the POST /api/v2/messaging/outbound/agentsless/messages endpoint.
HTTP Method: POST
Endpoint: https://{your-domain}.mypurecloud.com/api/v2/messaging/outbound/agentsless/messages
Headers:
Content-Type: application/json
Authorization: Bearer {access_token}
JSON Payload:
{
"to": "+15551234567",
"from": "+15559876543",
"message": "Your appointment reminder: Dr. Smith tomorrow at 10:00 AM. Reply STOP to opt out.",
"conversationId": "conv-8f4e2a1b-9c3d-4e5f-a6b7-8d9e0f1a2b3c",
"externalContactId": "ext-cust-998877",
"type": "sms",
"metadata": {
"campaignId": "appt-reminder-q3",
"triggerSource": "crm-scheduler",
"complianceCheck": "tcpa-verified-2023-10-15"
}
}
The Trap: Omitting the conversationId field or generating a new UUID for every message to the same contact. This forces Genesys Cloud to create a new conversation thread for each outbound message. Downstream effects include broken conversation history in WEM, inflated analytics counts, and compliance tracking fragmentation. Speech analytics and quality management tools cannot correlate messages to a single customer journey.
Architectural Reasoning: We enforce a deterministic conversationId strategy because Genesys Cloud uses this identifier to thread messages across channels and time. Your external system must generate a UUIDv4 on the first outbound interaction and cache it against the customer record. Subsequent messages reuse the same identifier. This preserves conversation state, enables accurate first-contact resolution metrics, and ensures that opt-out preferences propagate correctly across the thread. The externalContactId field serves as a secondary correlation key for CRM synchronization. We include metadata to pass business context through the pipeline without altering the message body, which keeps SMS content clean for carrier filtering.
3. Throughput Architecture and Rate Limit Mitigation
Genesys Cloud enforces throughput limits on outbound messaging to protect carrier relationships and prevent network congestion. The limits vary by license tier and carrier agreements, but sustained bursts without backpressure will trigger 429 Too Many Requests responses.
You must implement an exponential backoff queue in your integration layer. Monitor the Retry-After header in 429 responses and adjust your dispatch rate accordingly. Maintain a local queue with a maximum depth that matches your licensed throughput capacity. Implement circuit breaker logic to halt dispatch when failure rates exceed 15 percent over a rolling five-minute window.
The Trap: Implementing a fire-and-forget dispatch pattern without queue depth monitoring or circuit breaker logic. During peak scheduling windows, your external system will exhaust Genesys Cloud rate limits. The API will return 429 responses, but your system continues to queue requests. Memory consumption spikes, database connections pool out, and downstream processes stall. You experience cascading failures that require manual intervention to reset.
Architectural Reasoning: We architect throughput control at the integration layer because Genesys Cloud rate limits are enforced per tenant, not per API client. Your system must self-regulate. We use a token bucket algorithm to smooth dispatch rates and prevent burst spikes. The circuit breaker stops traffic when carrier rejection rates indicate a compliance or infrastructure issue. This prevents wasted API calls and protects your sender reputation. You also gain observability into queue depth, which allows you to scale dispatch workers dynamically based on actual throughput capacity rather than fixed schedules.
4. Delivery Status Webhooks and Dead Letter Queue Handling
Outbound messaging operates on an asynchronous delivery model. Genesys Cloud publishes delivery status events to a configured webhook endpoint. You must configure the webhook in Admin > Messaging > Agentless Messaging > Webhooks. Set the endpoint URL and enable retry logic with a maximum of five attempts over a two-hour window.
Webhook Payload Example:
{
"id": "msg-7a3b9c2d-1e4f-5a6b-7c8d-9e0f1a2b3c4d",
"type": "sms",
"from": "+15559876543",
"to": "+15551234567",
"conversationId": "conv-8f4e2a1b-9c3d-4e5f-a6b7-8d9e0f1a2b3c",
"status": "delivered",
"timestamp": "2023-10-27T14:32:15Z",
"deliveryStatus": "delivered",
"errorCode": null,
"metadata": {
"campaignId": "appt-reminder-q3",
"triggerSource": "crm-scheduler",
"complianceCheck": "tcpa-verified-2023-10-15"
}
}
The Trap: Processing webhook payloads synchronously within the request lifecycle. If your business logic takes longer than two seconds to execute, the webhook endpoint times out. Genesys Cloud marks the event as failed and begins retrying. You receive duplicate status updates, which corrupts delivery metrics and triggers redundant CRM updates. Your system appears to have delivery failures when the messages actually succeeded.
Architectural Reasoning: We decouple webhook ingestion from business processing because carrier delivery receipts are time-sensitive and must be acknowledged immediately. Your endpoint must return a 200 OK response within 500 milliseconds. You push the payload to a message broker (Kafka, RabbitMQ, or SQS) for asynchronous processing. This guarantees event receipt while allowing your system to handle processing delays offline. We implement idempotency checks using the id and conversationId fields to prevent duplicate state updates. Failed webhooks after maximum retries route to a dead-letter queue for manual inspection and reprocessing. This preserves data integrity and ensures that delivery status tracking remains accurate under load.
Validation, Edge Cases & Troubleshooting
Edge Case 1: Carrier Filtering and 10DLC Rejection
Failure Condition: Messages transition from queued to failed within 60 seconds. The API returns no synchronous error. Webhook events show deliveryStatus: "failed" with errorCode: "carrier_rejected".
Root Cause: The outbound content violates 10DLC campaign rules. Carriers reject messages containing unapproved links, promotional language, or mismatched sender IDs. Genesys Cloud does not validate content against carrier rules at dispatch time.
Solution: Implement pre-dispatch content validation against your 10DLC campaign parameters. Use Genesys Cloud’s compliance checking endpoint to verify message structure before dispatch. Maintain a content approval cache to avoid repeated validation calls. If rejections persist, audit your 10DLC campaign registration for category mismatches and update the approved template list.
Edge Case 2: Webhook Timeout and Event Loss
Failure Condition: Genesys Cloud logs show webhook delivery attempts failing after three retries. Your system records no delivery status updates. Conversations remain in pending state indefinitely.
Root Cause: The webhook endpoint exceeds the two-second response threshold. Network latency, database locks, or synchronous business logic processing delays the 200 OK response. Genesys Cloud interprets this as a delivery failure and stops retrying after the maximum attempts.
Solution: Refactor the webhook handler to acknowledge receipt immediately. Push the payload to an asynchronous queue and return 200 OK within 200 milliseconds. Implement a retry handler for your queue consumer to process failed events. Monitor webhook latency metrics and set alerts when response times exceed 800 milliseconds. This prevents event loss and maintains accurate delivery tracking.
Edge Case 3: Conversation Threading Breakdown
Failure Condition: Each outbound message creates a separate conversation thread. Analytics show inflated contact counts. Opt-out preferences do not apply to subsequent messages. WEM recordings lack context.
Root Cause: The external system generates a new conversationId for every API call instead of reusing the cached identifier. The externalContactId field is also inconsistent across calls.
Solution: Enforce a deterministic conversation state management pattern. Generate a UUIDv4 on the first outbound interaction and store it in the CRM record. Reuse the identifier for all subsequent messages to the same contact. Validate that externalContactId matches the CRM record exactly. Implement a validation middleware that rejects API calls with missing or mismatched conversation identifiers. This restores threading integrity and ensures compliance tracking operates correctly.