Network API Exposure
Today’s modern telecom network has a plethora of equipment and communication protocols. Different networks, protocols and equipment is involved to deliver the service dependent on the device’s capabilities, the user’s location, traffic load, the subscriber’s subscription and policy, the network and service policy and so forth. All of which is essential to deliver a fully-functional and useful service. Once this is in place, however, there are many useful services that can be delivered over this infrastructure – services that use the connectivity and transport layers – but do not need any awareness of these details.
Such services may be provided by the telecom operator, third parties with which they have a contractual arrangement or if desired, directly “over-the-top” by third parties where there is no permanent commercial relationship. The user authentication, security and service availability details are different for each of these, but the core requirement is the same: abstract the complexity of the underlying network elements to expose the service enablers and other operator/network capabilities such as charging interfaces using Application Programming Interfaces (API) for other IT systems to use.
Formerly, such network and service enabler API exposure was difficult to achieve and cumbersome to use. Nowadays however, modern IT systems typically expose their capabilities to other systems as web services APIs in a Service Oriented Architecture (SOA).
Network API Exposure for use by systems that are within and external to the MNO are shown below:

