The Parlay Group, a technical industry consortium, developed Parlay/OSA, an open API for the telephone network which include  call control, conferencing, user interaction.
The Parlay Group was a technical industry consortium (founded 1998, ended around 2007) that specified APIs for the telephone network. Parlay/OSA was an open API for the telephone network. It was developed by The Parlay Group, which worked closely with ETSI and 3GPP, which all co-publish it. Parlay APIs include: call control, conferencing, user interaction (audio and text messaging, SMS/MMS), and billing. 
