CTI RP in CCM 5.1.1b CFA to Voicemail.
Call Handler is configured to transfer back to an extension (with Hunt Group attached) during business hours.
If I call the Call Handler, Unity is playing the Call Handler greeting, rather than observing the transfer function.
How are you calling the call handler? This is critical information - if you're dialing the extension of the call handler from the opening greeting that's one scenario, if you're fowarding from an extension that is assigned to the call handler directly, that's another.
Another thing to check is make sure you're testing with the alternate transfer rule - this over rides the standard and off hours rules so you make sure you're working with the active rule that way.
If you're forwarding from extension "1234" and you have a call handler setup with "1234" then the transfer rule will be skipped by design - this is to prevent "Transfer loops" which can be deadly. You can get around this by chaining a couple call handlers together such that the "first call" flag is cleared. If that's not what you're doing, let us know since it's likely a configuration problem then.