DND is a FreePBX concept, not an Asterisk one. For the Asterisk queue system to consider the agent unavailable, without actually trying to call them, they would have to pause themselves in the queue.
This may help:
DND is a FreePBX concept, not an Asterisk one. For the Asterisk queue system to consider the agent unavailable, without actually trying to call them, they would have to pause themselves in the queue.
This may help: