hunt group caller ID carry forward issues

Hi there,

Looking for a mix of IVR and hunt group...

Customer requirement:
call comes in and rings 2 extensions for 20 seconds
no answer plays a message letting callers know the call is being forwarded
2 cells phones ring for 20 seconds (must include the caller ID)
no answer on the cells, the call goes to the voicemail box of one of the 2 original extensions.

Thoughts on the process?

Originally did:
hunt group:
1. extension based ring group (no message)
2. extension based ring group (with msg of forwarding) - needed to add one of the extensions...
3. IVR. plays the "please leave a msg" and the after 2 seconds, the no input forwards to one of the extension's voicemail.

The issue with the above hunt group is that the caller ID isn't carried forward.

Any suggestions on what will work for the customer requirements?

Thanks,

Ryley