How to organize the infrastructure?

Question

Cisco

Good afternoon. At the moment, there is such an infrastructure - two branches and a main office, but without IP telephony phones (marked on the map as "Phone") and devices ("Device" for which you need your own subnet)
Please help. Set up addressing on phones and devices (does each department need to allocate a subnet for phones and devices?) And what to write in routing and access lists on routers R1, R2, R3, ASA, so that everything is routed. All phones must be routed from the PBX. And all "Device" devices must go to the "DEVICE ROUTER" router, and from the "DEVICE ROUTER" side, the network 192.168.0.0/24 is announced for us (only from this subnet our "Device" devices can get to the "DEVICE ROUTER")
I would be grateful if someone describes the routing and access lists for each router that need to be registered.

Answer 1

Telephony:
Separate networks for telephones in each division

10.10.0.0/24
10.11.0.0/24
10.12.0.0/24

On the routers of departments - the route from the telephony network to the PBX (via vpn-link)
On the ACE - routes to the telephony networks through the necessary links.
Access is allowed only between telephony networks and PBX + access to the admin panel of phones and PBX from where you need
Devices:
Each division has separate networks for devices

10.20.0.0/24
10.21.0.0/24
10.22.0.0/24

On subdivision routers - the route from the device network to the device router
On the ace - routes to the device networks through the necessary links and the route to the device router
On R3 - routes to the device networks through the ace
Further - or negotiate with the device router - to pass your networks - or configure nat for device networks on R3
Access is allowed only between device networks and device router (well, admin panel)