Outbound call basically assists businesses and companies in reaching out to prospects, customers, suppliers, or partners with outgoing calls. This can be to support the sales team with telemarketing services such as appointment making, cold calling, warmup calling, sales leads, Campaigns, announcements, upselling services, or for market research. 

Outbound calls can often be combined with inbound calls, which are typically geared to receive incoming calls to your chosen number, to receive interested calls from prospects, customers, suppliers, or partners.

Read more about inbound calls, here