LAN routing design assistance

I’m blowing my brain up trying to figure out both a VLAN set up and LAN routing design for a new SIP service coming via a new 2nd ISP.

The equipment I manage is shared by two businesses and there are two VoIP telephone systems that I want to move to SIP.

The voice VLANs work aces and have done so for some time. All VLANs are routed via a HP switch (switch1). One VoIP telephone system is connected to another HP switch (switch2) and voice traffic for it (VLAN 17) is tagged through switch2.

The second VoIP telephone system is connected to a third HP switch (switch3) and it tags the traffic as VLAN 130.

I’ve recently signed up for a second ISP (for redundancy) with SIP connected via a Ubiquiti EdgeRouter which is connected to the third HP switch (switch3).

All of the switches are interconnected via fibre and are located in separate buildings.

The SIP service has an external IP address and I can ping it via the new service. I’m able to indentify each SIP service with its own username and password.

My fundamental question is how do I design the internal routing so that SIP calls are routed to the telephone system/s and the EdgeRouter correctly? Do I assign an IP address from each voice VLAN on an interface on the EdgeRouter or does that occur at switch3?

Thanks!!