I am using ring_ready to let incoming calls to my IVR app ring couple times before the app engages:

session:execute("ring_ready");
session:sleep(8000);
...
session:answer();

On one of my servers I am using freeTDM to interface with Sangoma hardware, and another uses OpenZap (this is really the only difference between the two FS instances). Ringing/early media is playing on the openzap server, but not with freeTDM. Any idea why not?