10.1.4.1. Internal Access Point Call 
Figure 167. Signaling for an internal access point call
Signaling from and to the connected telephones is always transmitted
over the IP network to the call processing infrastructure in the OpenScape
4000 central system, and from there back again.
Figure 168. Voice link (payload) for an internal access point call
The central call processing infrastructure establishes the voice link
and makes all features available. In this case, the voice link is switched
within the access point in the TDM-based switching network of the HG
3575 module. This means that no payload is generated in the IP network
and none of the channels of the transport capacity from the access point
to the IP network are occupied.