From http://www.cisco.com/warp/public/cc/pd/si/casi/ca3500xl/prodlit/cfig3_an.htm
" Scenario 2: Configuration of switch connected to daisy chain of IP phones
This scenario may be more common in a call center environment (Figure 3 below). Cisco IP phones are connected in a daisy chain fashion without any PC attached at the far end. The Catalyst 3500 XL switches should be configured such that the first IP phone treats all other Cisco IP Phones connected to itself as trusted devices. Thus, any voice call from any of the IP phones in the daisy chain will get the same high priority as the first IP phone.
Note: All voice and data traffic on the port in this configuration will have the same priority. Hence, we strongly recommend users not to connect any workstations at the far end of the Cisco IP phone daisy chain since both the voice and data traffic in this scenario will get the same high priority and may adversely affect the quality of voice calls."
Hope that helps.
Mike