When registering IP (SCCP) phones to CME, it is generally stated that the phones should be in the same local network.
I used to think that this meant the same IP subnet and VLAN as the CME, but found out that phones in subnet 192.168.5.x can register with CME on 192.168.1.x network, as long as inter-vlan routing is configured.
At the same time, I see posts about restrictions on IP phones registering to CME over a WAN.
Apart from speed, what is the difference between WAN and LAN at layer 3?
How would an IP phone on a WAN, be treated any differently than one on a different subnet on a local lan ?