Subscribe to UPS Track Alert API to receive push webhook notifications for shipment status changes

Steps

1. Authenticate via UPS OAuth 2.0 to obtain a Bearer token
2. POST to /api/track/v1/subscription/anchor with your callback URL, tracking number, locale, and transaction type to register a webhook subscription for a specific shipment
3. UPS will POST status events to your callback URL as shipment milestones occur; each payload includes tracking number, activity description, location, and timestamp
4. Return HTTP 200 from your callback within the required timeout; failed callbacks trigger UPS retries
5. To unsubscribe from alerts for a shipment, DELETE /api/track/v1/subscription/{subscriptionId}