SMS delivery is the distribution of SMS messages to end-user mobile devices (i.e. Mobile Terminated SMS) or the delivery to an application of messages from mobile devices (i.e. Mobile Originated SMS). Delivery of SMS to or from an application can involve an SMS gateway operated by an SMS aggregator who would provide SMS APIs with which to communicate with the application.
See Melrose Labs Tyr SMS Gateway
Melrose Labs: Our mission is to deliver pivotal services in cloud communications across mobile, fixed-line and internet for enterprises of all sizes. Through these services, we help businesses and other organisations communicate better with their staff and customers, and by doing so increase their success.