Properly Deploying IP Phones / SIP Trunk VLAN - Layer 3 Switch

Hello all,

Looking for suggestions on my thoughts on Deploying IP Phones and a SIP Trunk on my customers Layer 3 Ubiquiti Switch.

I am thinking I will have them set up a Voice VLAN and use that VLAN for the:

LAN of the IPO
Ports for the IP/SIP Phones

WAN to their Data Side to allow access internally from their PC's

Now here is where I get a bit confused, as I am not real familiar with Prioritizing Voice Packets and QoS. Would it be best to include the SIP Trunk out the LAN on the IPO on the Voice VLAN? They should be able to Prioritize and set up QoS on my voice VLAN on the Layer 3 Switch, correct?

Thoughts? Suggestions?

ACSS