conversations over the internet

Hi everybody

I run an Internet page for blind and otherwise visually impaired users and have some thoughts on making a talk (audio) support/dialogue feature. The most basic implementation could be as simple as a text chat, only using sound instead, of course.

I know this may not be the only relevant place to post this issue, but i was wondering if any of you guys have heard of something to integrate into Drupal? It would really be a giant step for challenged computer users if audio support and dialogue was more common on websites, but I can't seem to find any general, open source, free and minimal projects at all.

Best,
Simon