Tracking Number and Tracking

The tracking number is the central identifier of every parcel shipment in e-commerce fulfillment. It connects the warehouse, carrier, shop system, and end customer in a seamless chain. Without a correctly generated, transmitted, and communicated tracking number, tracking remains blind – and with it the ability to meet delivery promises, reduce support workload, and ensure customer satisfaction.

In this glossary entry, you will learn how tracking numbers are created, which tracking events are relevant, how systems work together, and which errors occur most frequently in day-to-day operations.

What is a tracking number?

A tracking number – also called a tracking ID, parcel number, or waybill number – is a unique identifier assigned to a shipment by a carrier. It enables tracking of the parcel from handover at the warehouse to delivery to the recipient.

Typical characteristics:

• Uniqueness: Each shipment receives exactly one number; duplicate assignments lead to confusion.
• Carrier-specific format: DHL, DPD, GLS, and UPS use different lengths and character sets.
• Machine readability: The number appears on the shipping label and is scanned via barcode.
• Cross-system reference: WMS, ERP, shop, and carrier API all reference the same ID.

The tracking number must not be confused with the order number or SKU. The order number identifies the customer order in the shop; the tracking number identifies the physical parcel in transit.

Tracking: Shipment tracking in the fulfillment context

Tracking refers to the ongoing capture and communication of status changes for a shipment. Every scan or system entry at the carrier generates a tracking event – for example, "Accepted at parcel center", "Out for delivery", or "Delivered".

For online retailers, tracking reduces WISMO inquiries, supports claims handling, and provides KPIs such as delivery rate and transit time.

Process flow: From tracking number to customer tracking

Difference: Tracking number, tracking link, and tracking URL

How is a tracking number created in the fulfillment process?

The tracking number is typically assigned automatically as soon as a shipping label is generated in the warehouse. The typical flow in the pick-pack-ship process looks like this:

1. Order release: The WMS receives a shipment-ready order from the shop or ERP.
2. Picking and packing: Items are picked, checked, and packed.
3. Label request: The shipping software sends shipment data (weight, dimensions, address, product) to the carrier API.
4. Number assignment: The carrier responds with tracking number, label PDF, and optional tracking URL.
5. Booking and handover: The parcel is marked as "shipped" in the system; the number flows back to the shop and customer communication.
6. First scan event: When the parcel enters the carrier network, the first visible tracking status appears.

Important tracking events and their meaning

Carriers differ in the granularity of their status updates. Nevertheless, most events can be grouped into overarching categories:

Standard events in domestic shipping

• Electronic shipment data transmitted: Label created, parcel not yet with carrier.
• Acceptance / drop-off: Parcel in carrier network; tracking becomes visible to customers.
• Sorting at hub: Transit between hub and delivery depot.
• Out for delivery: Parcel on delivery vehicle en route.
• Delivered: Successful handover to recipient or neighbor.
• Delivery attempt failed: Recipient not available, pickup notice issued.
• Return to sender: After multiple failed attempts or undeliverable address.

Typical domestic tracking flow

The phase between label creation and the first scan is often confusing for customers – proactive communication pays off here.

International shipments

For cross-border shipping, events such as customs declaration and customs clearance are added. The tracking number may change or be supplemented by an international reference – a common stumbling block in customer communication.

System integration: WMS, carrier API, and shop

A tracking number only delivers its full value through seamless system integration. Three layers must work in sync:

WMS and shipping software

The warehouse management system or dedicated shipping software (multi-carrier platform) communicates via API with DHL, DPD, GLS, and other providers. The returned tracking number is assigned to the order in the WMS and transmitted to the shop via webhook or batch export.

Shop and order management

In the shop system, the number appears in the customer account, in the shipping confirmation email, and optionally in order history. Modern shops support automatic status updates via carrier webhook – the customer sees "In transit" or "Delivered" without visiting the carrier website.

Tracking aggregators

With multi-carrier strategies, many retailers use tracking platforms that normalize events from different carriers. This unifies the display and enables centralized analytics.

Tracking number data flow

Return channel: Carrier events → tracking aggregator → shop notification

Best practices for tracking number and tracking

Professional tracking does not start with the customer, but in warehouse operations. The following principles have proven effective in practice:

Communication

• Send shipping confirmation within minutes of label printing.
• Include tracking number, carrier name, and direct tracking link.
• Communicate realistic delivery windows – not just the optimistic carrier promise.
• Proactively inform about delays before the customer asks.

This aligns with customer expectations for delivery times and transparency in modern e-commerce.

Technical reliability

• Escalate API errors during label creation immediately; no "silent" failed attempts.
• Validate tracking numbers before shipment (format, length, check digit).
• Avoid duplicate label prints – they create two numbers for one parcel.
• Regularly reconcile tracking events against internal shipment lists.

Last mile and delivery quality

The last mile is the phase with the most customer touchpoints. Tracking events in this phase – "Out for delivery", "Forwarded to parcel locker", "Delivered" – shape the customer experience more than any marketing message.

Common errors and how to avoid them

Even experienced fulfillment teams struggle with recurring problems around tracking numbers:

1. Shipping confirmation without number: Label API returns error, email is sent anyway.
2. Wrong number in shop: Copy-paste error or mix-up during batch upload.
3. Delayed first scan event: Parcel sits in warehouse, handover to carrier only happens the next day.
4. Multiple numbers per order: Partial shipment without clear assignment confuses customers.
5. Outdated tracking link: Carrier changes URL structure, deep links no longer work.

Checklist: Setting up tracking number and tracking correctly

• Shipping software connected via API to all carriers in use
• Automatic tracking number transfer to WMS after label print
• Return channel WMS → shop configured for shipping confirmation
• Email template includes number, carrier, and tracking link
• Customer account shows live status or link to carrier
• Process for partial shipment: one separate number per parcel
• Escalation rule defined for missing scan after 24 hours
• Monthly reconciliation: shipped orders vs. tracking events
• Packing team training: no shipment without successful label print
• Data privacy: tracking number only to authorized recipients

Tracking number in the overall process: From order to delivery

The tracking number is the final digital stamp in the chain from order receipt to delivery. Only when picking, packing, and label creation run without errors can tracking fulfill its purpose.

For fulfillment service providers, correct number assignment is part of the contractual SLA. Missing or delayed tracking data can lead to marketplace penalties – especially on Amazon, eBay, and Otto, where proof of shipment and scan events are monitored.

Tracking maturity level comparison

Conclusion

The tracking number is far more than a string of characters on a label. It is the link between physical shipping and the digital customer experience. Those who reliably generate tracking numbers, distribute them across systems, and actively communicate tracking events reduce support costs, build trust, and meet the expectations of modern online buyers.

Investments in API integration and automated notifications pay off especially during periods of high order volume.

Related topics

• Shipping and tracking terms – overview
• Pick-Pack-Ship – The shipping process in the warehouse
• Customer expectations and delivery times
• Last mile – The final mile to the doorstep
• Order to delivery – The complete fulfillment workflow

Last updated: July 6, 2026