Steve, Thanks for bringing that to my attention.  The 2724 User Guide does not have any information about Voice VLANs.  That is going to be your primary option in separating Voice traffic from all other traffic on the network.  That is the reason for my response.  The naming convention for the Power connect switches is the higher the series number the more features and configuration options you have. Your all set if you have the 6224 and 5448 available.  Sorry for any confusion.
Hello, I have a branch office that uses several Dell PowerConnect switches (2716's and 2724's). This office also runs VoIP. I need a way to prioritize the VoIP traffic over all other traffic across these switches. Can the Dell PowerConnect switches do this? I an doing some research and it looks like I might be able to but I'm not positive either. Any help would be most appreciated. Thank you, -Steve    
QoS for VoIP on Dell PowerConnect switches