The OB/L (Ocean Bill of Lading) number is typically provided by the shipping line. It is assigned by the shipping line as a unique identifier for the specific bill of lading issued for the shipment. However, in some cases, the freight forwarder may also play a role in obtaining and providing the OB/L number, especially if they are acting as an intermediary between the shipper and the shipping line. The specific arrangement may vary depending on the contractual agreements and responsibilities between the parties involved in the shipment.