Jim,
I don't think the caller can choose to turn of the MOH at will. Would changing the music to something else less 'irritating' be an acceptable solution?
Rich, you may use the Call Hold and Call Unhold steps to add music to the queue.
How To Add MOH to ICD Caller in Queue
http://www.cisco.com/en/US/products/sw/custcosw/ps1846/products_configuration_example09186a0080159eb5.shtml
On the CTI ports that support the ICD application, the User Hold Audio Source is where you can choose which music to play to the callers in the queue.
The Call hold step is also described here.
http://www.cisco.com/en/US/docs/voice_ip_comm/cust_contact/contact_center/crs/express_5_0/programming/script_devp/editor_step_ref/crs501sr.pdf
Hope this helps.
Michael.
