This scenario lacks many details but I can make some assumptions. If you want a single voice vlan for both sites, then either the access switches or the L3 switches need a trunk port between them and a single voice vlan created in both L3 and access SW's. If you can not do a trunk port between sites, then create a seperate voice vlan on eace pair of switches (access and L3 respectively)
1. Create voice vlan x in L3 SW1 and access SW1.
2. Creat voice vlan y in L3 SW2 and access SW2.
3. Terminate an IP address from your new pool on the " interface vlan x/y" in the L3 SW's, this should serve as the default gateway for the phones.
4. Add "switchport voice vlan x/y" to each port on the access SW's that need a phone attached to it.
5. All routes should be updated for your voice gateways and call servers to get to your phones.
This is the basics and assumes you are using Cisco as indicated in your diagram.