Ask an English expert what to say if I call the hotel switchboard and ask her for the phone number of the purchasing manager.

if you are at the front desk, you must change, and you don't seem to know the other party's architecture, so

excuse me, I'd like to get the procurement department. could you help to transfer ... or give me the extension number?

(Then...transferring...)

May i speak to your procurement manager? Is her available now? ... class =' class1' > procurement is better than purchasing, because it would be strange for a big company to be called purchasing ...