Twilio offers various cutting-edge solutions for adding Speech Recognition and Text-to-speech (TTS) functionality to applications, including Say, Voice Intelligence Transcripts, ConversationRelay, and more. However, it's also possible to locally transcribe and generate audio using open-source technologies like Vosk, Bark, and others. These local options can provide benefits such as reduced storage costs and improved security, but may require more development effort. Vosk is an offline speech recognition library that uses machine learning models trained to convert spoken language into written text, while Bark is a transformer-based text-to-audio model created by Suno. Voice Puppet uses an audio file of speech to 'clone' the voice for use in generating TTS. The underlying technologies have been around for decades, but recent developments and accelerated research have made AI-powered telephony features more accessible and easy to use than ever.