Twilio Voice is a programmable voice API that lets web and mobile applications make and receive phone calls, either over the public telephone network (PSTN) or over the internet using VoIP. Developers use it to build IVR, call recording, speech recognition, text-to-speech, conferencing and call transcription. Elastic SIP Trunking connects existing phone systems to the telephone network, and SDKs are available for iOS, Android and JavaScript. The service is delivered as a cloud API.
Twilio Inc. is a US company; according to its data protection addendum, transfers of personal data from the EEA to Twilio in the United States rely on the EU-US Data Privacy Framework, standard contractual clauses and binding corporate rules. Since December 2021 Twilio has offered a Voice region in Ireland, which, according to Twilio, lets you control where Voice data is ingested, processed and stored. You have to select that region explicitly: an access token without a target region uses the default US region. The software is not open source.