THECALLR .NET SDK by THECALLR communicates with the API to access telephony data such as voice and messaging, useful to integrate into smartphone applications. Resources on GitHub include samples that demonstrate call tracking, click to call, media, and SMS.
AISpeech is the API behind a Chinese language and pronunciation learning website, AIChinese. You may know that Chinese is a tonal language. Where tones and inflection are used in English to convey emotion or differentiate between a declarative statement and a question, in tonal languages like Chinese, different tones on the same syllable can be altogether different words. The AISpeech API gives you access to a language processing engine which is capable of detecting spoken words and evaluating if the appropriate tone is used.