i have a question i'm configuring an uc520. i configured an ip to the physical wan interface however the ip address under telephony-service belongs to a different subnet do you guys recommend that kind of implementation or should i assign the same ip address to the cme ?
Generally, you would not assign the WAN address under telephony-service. The telephony-service address is the address to which your phones will register and will usually be either the loopback or the voice VLAN address.
Hope this helps.