Table of Contents
Advertisement
Glossary
458
Gateway
Entrance and exit, transition point
Half duplex
Bidirectional communication method in which it is only possible to
either send or receive at a particular point in time. Also known as
Simplex.
Handheld unit
Mobile component of wireless telephone units. In the event of digital
transmission, it is also possible to make telephone calls between the
handheld units (DECT).
Hands free
If the telephone has a microphone and speaker installed, you can
conduct a call without using your hands. As a result, other people in
the room can also participate in the call.
Hashing
The process of deriving a number (hash) from a character string. A
hash is generally far shorter than the text flow it was derived from.
The hashing algorithm is designed so that there is a relatively low
probability of generating a hash that is the same as another hash
generated from a text sequence with a different meaning. Encryption
methods use hashing to make sure that intruders cannot change
transmitted messages.
HDLC
High Level Data Link Control
HDSL
High Bit Rate DSL
HDSL2
High Bit Rate DSL, version 2
Headset
Combination of headphones and microphone as a useful aid for
anyone who makes a lot of telephone calls and wants to keep hands
free for making notes.
HMAC
Hashed Message Authentication Code
HMAC-MD5
Hashed Message Authentication Code - uses Message Digest Al-
gorithm Version 5.
HMAC-SHA1
Hashed Message Authentication Code - uses Secure Hash Al-
gorithm Version 1.
Holding a call
A telephone call is put on hold without breaking the connection
(inquiry/brokering).
Holding in the PBX
Both B channels of the ISDN connection are needed for the per-
formance features "Call another person during a call" and "Speak al-
ternately with two people" (brokering). As a result, you cannot be
reached from outside or make external calls via your PBX's second
Funkwerk Enterprise Communications GmbH
R1xxx/R3xxx/R4xxx
Advertisement
Table of Contents
