Grandstream Networks Grandstream GXV-3000 - Manual (Page 60)

GXV-3000 User Manual
Grandstream Networks, Inc.
- 60 -
The intent of H.264/AVC has been to create a standard that would be capable of providing
good video quality at bit rates that are substantially lower (e.g., half or less) than what previous
standards would need (e.g., relative to
MPEG-2 , H.263 , or MPEG-4 Part 2 ).
HTTP
Hyper Text Transfer Protocol; the World Wide Web protocol that performs the request and re-
trieve functions of a server
IP
Internet Protocol. A packet-based protocol for delivering data across networks.
IP-PBX
IP-based Private Branch Exchange
IP Telephony
(Internet Protocol telephony, also known as Voice over IP Telephony) A general term for the
technologies that use the Internet Protocol's packet-switched connections to exchange voice,
fax, and other forms of information that have traditionally been carried over the dedicated cir-
cuit-switched connections of the public switched telephone network (PSTN). The basic steps
involved in originating an IP Telephony call are conversion of the analog voice signal to digital
format and compression/translation of the signal into Internet protocol (IP) packets for trans-
mission over the Internet or other packet-switched networks; the process is reversed at the re-
ceiving end. The terms IP Telephony and Internet Telephony are often used to mean the same;
however, they are not 100 per cent interchangeable, since Internet is only a subcase of packet-
switched networks. For users who have free or fixed-price Internet access, IP Telephony soft-
ware essentially provides free telephone calls anywhere in the world. However, the challenge
of IP Telephony is maintaining the quality of service expected by subscribers. Session border
controllers resolve this issue by providing quality assurance comparable to legacy telephone
systems.
IVR
IVR is a software application that accepts a combination of voice telephone input and touch-
tone keypad selection and provides appropriate responses in the form of voice, fax, callback, e-
mail and perhaps other media.
MTU
A Maximum Transmission Unit (MTU) is the largest size packet or frame , specified in octet s
(eight-bit bytes), that can be sent in a packet- or frame-based network such as the Internet. The
maximum for Ethernet is 1500 byte.
NAT
Network Address Translation
NTP
Network Time Protocol
, a protocol to exchange and synchronize time over networks
The port used is UDP 123
Grandstream products using NTP to get time from Internet