Asterisk ConfBridge and MeetMe
From Wildsong
Things changed at version 12. It's covered in the Asterisk documentation on Bridges
MeetMe used to be how you set up a conference bridge. MeetMe requires DAHDI support even if you had no PSTN hardware (and therefore no other need for DAHDI.)
Configuration for ConfBridge
https://wiki.asterisk.org/wiki/display/AST/Asterisk+13+Configuration_app_confbridge
Application https://wiki.asterisk.org/wiki/display/AST/Asterisk+13+Application_ConfBridge