http://www.cisco.com/en/US/products/hw/switches/ps607/products_qanda_item09186a0080116ffe.shtml#q15
From the link:-
Configure the ports connected to non-Cisco IP phones (which can not tag dot1p value) by issuing the switch priority default <4-7> command so that those frames are queued in the high priority queue. Remember that all traffic received on this port would be prioritized and hence avoid connecting PC or other data traffic devices on this port.
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So, if your non-Cisco IP phone can tag frames with 802.1p, then the CoS value from those phones will be trusted by the switch (by default). For untagged frames from the PC, you can use the command "switchport priority default 0" to set the frames from PC to CoS 0 (this is also enabled by default). I believe you can do only this much with this switch.
If your non-Cisco IP phones do not support 802.1p tagging, then the frames are sent to the switch port as untagged. In that case, you have to use command "switchport priority default 5" to set the CoS value of the phone to 5. If you have PCs connected to the Phone, then the PC's traffic will also be prioritied which is not desirable. It is recommended that PC not be connected to non-Cisco phones which donot support 802.1p tagging.
So, check if the non-Cisco IP phones support 802.1p tagging and what value they tag the frames with.
