Hi,
Call Classification (OnNet/OffNet) can be configured on the Route Pattern or gateway device itself. Call Classification indicates whether the call that is routed through this route pattern is considered either off (OffNet) or on (OnNet) the local network.
So if the ipphone receives a call from a route pattern that is set as OffNet then there
will be a distinctive ring for the offnet party calling.
You should be able to notice that calls classified as Offnet will have a short ring.
Offnet calls will have two short rings followed by a gap then two short rings and so on.
Onnet calls will have one long ring, followed by a gap, then one long ring .