When you book a shipment in with DPD, they will respond by sending a consignment number and parcel number(s), both of which can be used to track the shipment.
You can select which one you'd like to receive my going into your DPD advanced settings (which can be found by scrolling to the bottom of the page and clicking on the little grey cog) and clicking on the below drop down menu.
When this has been selected and saved, the selected option will be returned as your shipment tracking number made available in Shiptheory as well as being sent back to your shipment's original channel.
Note: If you select 'Parcel number' as the tracking number option, for multi-parcel consignments, the parcel number for the first parcel in the consignment will be returned as the tracking number.
If you have any further queries feel free to contact support