Billing systems initially gained distribution in the sphere of telecommunication services. Now these systems are widely applied in all spheres where there is an interaction between the seller (service provider) and the buyer (the subscriber, the consumer of services). In my opinion, the broadest opportunities of application have bank billing systems. From my report you learn: - What is BBS, its main functions. - How is the integration testing of BBS held. With what systems BBS most often interacts, possible schemes of connection of BBS and other systems. - What is it necessary to pay attention on before carrying out testing of BBS. - You would know how to get prepared for an integration testing of BBS with adjacent systems in advance with high degree of readiness for testing.