Africa's Talking Airtime PHP Sample Code demonstrates how to use the API to access the time spent talking on a mobile phone. Developers will need an AfricasTalking username and APIKey for any request to the API.
The Nexmo SMS API is a service that allows you to send and receive SMS messages anywhere in the world. Nexmo provides REST APIs, but it's easier to use their official Java SDK. This tutorial covers how to send and receive SMS messages with the SDK so that you can use them in your applications.