Glossary - Siemens Gigaset C450IP Owner's Manual

Glossary

Glossary
A
ADSL
Asymmetric Digital Subscriber Line
Special form of DSL.
ALG
Application Layer Gateway
NAT control mechanism of a router.
Many routers with integrated NAT use
ALG. ALG lets the data packets in a VoIP
connection pass and adds the public IP
address of the secure private network.
The router's ALG should be deactivated
if the VoIP provider offers a STUN server
or an outbound proxy.
See also: Firewall, NAT, Outbound
proxy, STUN.
Authentication
Restriction of access to a network/serv-
ice by use of a password to log in.
Automatic ringback
See Ringback when the number is
busy.
B
Block dialling
Enter the complete phone number, and
correct it if necessary. Then pick up the
receiver or press the handsfree key to
dial the phone number.
Broadband Internet access
See DSL.
C
Call forwarding
CF
Automatic forwarding of a call to a dif-
ferent telephone number. There are
three kinds of call forwarding:
– CFU, Call Forwarding Unconditional
– CFB, Call Forwarding Busy
– CFNR, Call Forwarding No Reply
86
Call waiting
VoIP provider feature. A beep during a
call indicates that another caller is wait-
ing. You can accept or reject the second
call. You can activate/deactivate the
feature.
CF
Call Forwarding
See Call forwarding.
Client
Application that requests a service
from a server.
Codec
Coder/decoder
Codec is a procedure that digitises and
compresses analogue voice before it is
sent via the Internet and decodes –
i.e.translates into analogue voice – dig-
ital data when voice packets are
received. There are different codecs
that vary, for instance, according to the
level of compression.
Both parties involved in the telephone
connection (caller/sender and recipi-
ent) must use the same codec. This is
negotiated between the sender and the
recipient when establishing a connec-
tion.
The choice of codec is a compromise
between voice quality, transmission
speed and the necessary bandwidth. A
high level of compression, for example,
means that the bandwidth required for
each voice connection is low. However,
it also means that the time needed to
compress/decompress the data is
greater, which increases execution
time for data in the network and thus
impairs voice quality. The time required
increases the delay between the sender
speaking and the recipient hearing
what has been said.