there are a couple of options to have no MOH on just some phones
one would be to create a blank MOH
Q. How to disable Music on Hold?
http://www.cisco.com/en/US/partner/products/sw/voicesw/ps556/products_qanda_item09186a0080094766.shtml#q20
the other one would be to take the MOH server from the MGRL from the phones you don't want to have MOH, in this scenario they would get Tone On Hold
HTH
HTH
java
if this helps, please rate