Courier Activities ISIC Code 5320. This class includes courier activities not operating under a universal service obligation. This class includes Pickup, sorting, transport, and delivery (domestic or international) of letter-post and (mail-type) parcels and packages by firms not operating under a universal service obligation. One or more modes of transport may be involved and the activity may be carried out with either self-owned (private) transport or via public transport, distribution and delivery of mail and parcels, and Home delivery services.