Internet Telephony - Internet telephony
refers to communications services-voice, facsimile, and/or voice-messaging
applications-that are transported via the Internet, rather than
the public switched telephone network (PSTN).
Cisco ATA 186 - It is a handset-to-Ethernet
adaptor that interfaces regular analog telephones with IP-based
telephony networks. By turning any analog telephone into an IP
telephone, the Cisco ATA 186 addresses the needs of the emerging
market of voice-over-IP (VoIP) services.
SIP - The session initiation protocol
(SIP) is about initiation of interactive communications sessions
between users. SIP also handles termination and modifications
of sessions as well. SIP actually doesn't define what a "session"
is; this is described by content carried in SIP messages. Most
of SIP is about the initiation part, since this is really the
most difficult aspect. "Initiating a session" requires
determining where the user to be contacted is actually residing
at a particular moment. The user is located and the session description
is delivered first and then SIP is used to convey the response
to the session initiation (accept, reject, etc.). If accepted,
the session is now active. SIP can be used to modify the session
as well. Doing so is easy - the originator simply re-initiates
the session, sending the same message as the original, but with
a new session description.
H.323 - H.323 was originally promoted
as a way to provide consistency in audio, video and data packet
transmissions in the event that a local area network (LAN) did
not provide guaranteed service quality (QoS). Although it was
doubtful at first whether manufacturers would adopt H.323, it
is now considered to be the standard for interoperability in audio,
video and data transmissions as well as Internet phone and voice-over-IP
(VoIP) because it addresses call control and management for both
point-to-point and multipoint conferences as well as gateway administration
of media traffic, bandwidth and user participation.
Packet Switching - This technique is
analogous to a telegraph connection. A network technology in which
data is broken into units called packets. For the data transfer
to take place a dedicated connection is not required to be established.
As and when the node gets free, the data is transmitted towards
the destination.
Circuit Switching - This switching
technique is analogous to a telephone connection. For a data transfer
to take place a dedicated connection is to be established prior
to data transfer. Unless a dedicated connection is established
data transfer cannot take place.
PSTN - PSTN (public switched telephone
network) is the world's collection of interconnected voice-oriented
public telephone networks, both commercial and government-owned.
It's also referred to as the Plain Old Telephone Service (POTS).
It's the aggregation of circuit switching telephone networks that
has evolved from the days of Alexander Graham Bell. Today, it
is almost entirely digital in technology except for the final
link from the central (local) telephone office to the user.
Codec - Codec is a bit of engineering
jargon, a short form of "encoder/decoder", which describes
a device capable of performing transformations on a data stream
or signal. Such devices can both put the stream or signal into
an encoded form (often for transmission, storage or encryption)
and retrieve, or decode that form for viewing or manipulation
in a format more appropriate for these operations. Codecs are
often used in videoconferencing and streaming media solutions.
Gatekeeper - The gatekeeper is the
most powerful management tool available for an H.323/SIP multimedia
network. As the brain of the H.323/SIP network, this application
performs essential control, administrative, and managerial functions
required to maintain the integrity of networks in both enterprise
and carrier environments.
Courtesy: Shilpa Garg (Corporate)
