There are couple of different ways to do this:
Assuming that the switch and every other device in between to the router is trusting QoS marking, you could match based on DSCP marking
class-map match-any VOICESIGNAL
match ip dscp cs3
class-map match-any VOICEDATA
match ip dscp ef
policy-map VOICE
class VOICEDATA
priority percent 20
class VOICESIGNAL
bandwidth percent 3
class class-default
fair-queue
random-detect (If needed)
Apply the above the policy-map to the WAN interface and add the bandwidth statement on this interface with the correct bandwidth that is available.
If its not possible to prioritize based on DSCP marking, you might have to look into ACLs. Basically match traffic that is going out using UDP port 16384 to 32767 as VOICEDATA and assign it EF and set priority percent as mentioned above. For signaling, you can match based on TCP/UDP - 5060, TCP -1720, TCP - 2427, TCP - 2000 and other ports as needed and assign it CS3 and use the same configuration as above..
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