3.10.1. Feature Description 
The OpenScape 4000 offers an IP-based connectivity between the OpenScape
4000 SoftGate (communication service signaling/media control unit) and
the endpoints. These endpoints can be:
- The full OpenScape 4000 feature sets. The abbreviation HFA is used for this functionality in the following sections.
- The Universal Feature Access IP sets. The abbreviation UFIP is used for this functionality in the following sections.
- Classic SIP devices (HW or SW clients) used for VoIP (Voice over IP) communication.
A secure IP (TLS/SSL-based) operating mode, called SPE (Signaling and
Payload Encryption), is supported - signaling and payload connections
for HFA and SIP subscribers are always encrypted even if SPE is not activated.
The OpenScape 4000 functionality can also be used on the phones in
the user's remote office. The IP connectivity (HFA, SIP/UFIP) via the
public internet to OpenScape 4000 SoftGate is therefore incorporated.
The OpenScape 4000 SoftGate is located with one interface in the public
network (WAN interface) and the other interface in a corporate network
(IPDA interface).
There is also implemented an extended support for SoftGate side DNAT
(DMZ) use cases.
See RN (Release Note) for latest information about this improvement.
See Section 14.2.4,
“DMZ” for more information about DMZ configuration.