FirstSource,
I don't think that DND ON misunderstood what you were asking, but they were providing you with the solution to fix the current issue.
Most likely the Operator has "messaged" the person's phone which will light the message notification button. When they press the flashing light it will ring the Operator until they answer the call or they cancel the message via MSG *.
The system is working as designed, but most likely you were never trained to know how to message a phone directly in order for someone to call you back. This can cause some confusion as you think the blinking message notification light only means it is a voice mail message from your mailbox when in reality the message notification button can be light by more than just the voice processing system.
Thanks,
TE