Snom ONE IP, Техническое руководство

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snom ONE • Administrator Guide, Release 5
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DHCP (Dynamic Host Configuration Protocol)
The TCP/IP protocol for allocating IP addresses dynamically when they are
needed. Devices running DHCP do not need a pre-configured IP address to join
an IP-based network. As devices join the network, IP addresses are given, and as
devices exit the network, IP addresses are released. DHCP is used by Internet ser-
vice providers (ISPs) to allow customers to join the Internet. The DHCP protocol
reduces system administration workload, allowing networks to add devices with
little or no manual intervention.
DID (Direct Inward Dial)
A feature offered by telephone companies for use with their customers’ private
branch exchange (PBX) systems. In DID service, the telephone company pro-
vides one or more trunk lines to the customer for connection to the customer’s
PBX and allocates a range of telephone numbers to this line (or group of lines)
and forwards all calls to such numbers via the trunk. As calls are presented to
the PBX, the dialed destination number (DNIS) is transmitted, usually partially
(e.g., last four digits), so that the PBX can route the call directly to the desired
telephone extension within the organization without the need for an operator or
attendant.
DID numbers are assigned to a communications gateway connected by a trunk
to the public switched telephone network (PSTN) and the VoIP network. The
gateway routes and translates calls between the two networks for the VoIP user.
Calls originating in the VoIP network will appear to users on the PSTN as origi-
nating from one of the assigned DID numbers.
DISA (Direct Inward Service Access)
The process of how incoming calls are handled by a telephone system. It allows
the external subscriber to make calls by dialing the extension or trunk subscriber
directly without assistance of an operator. It compensates for the shortcomings of
DIL and DDI.
DMZ (DeMilitarized Zone)
A computer or network zone that sits between a trusted zone (typically a LAN)
and an untrusted zone (typically the Internet). A DMZ is usually separated by
firewalls at each border and is used for servers (e.g., FTP) which are accessed from
untrusted networks.