10.47.1. Feature Description 
Servers, routers, MCU and similar equipment can be connected to
OpenScape 4000 as a tie line or station. From the point
of view of the protocol it is better to install these stations with SBCSU
because in this case OpenScape 4000 offers the network part of the protocol
and the terminal provides the user part. With tie line signaling differences
frequently occur in the protocol if the terminal has not actually implemented
the protocol for it. If more than one extension number is needed for
the connection these are provided with MSN.