IP PHONE

An IP Phone is a broadband hard phone, a self contained IP telephone that looks just like a conventional phone but instead of a conventional phone jack, it has an Ethernet port through which it communicates over a network using open standard -based IP. IP phones combine the functions of a traditional telephone with an Ethernet connectio. Since an IP phone communicates directly with a VOIP based system, neither it does require any personal computer nor any software running on a personal computer to make or receive VOIP phone calls. It can be used independenly, all that is required is an internet connection.

What is VOIP?

VOIP is Voice Over Internet Protocol. It uses the IP to transmit voice as packets over an IP network, so VOIP can be achieved on any data network thatuses IP, like the Internet, Intranets and Local Area Networks (LAN). In VOIP, the analog voicesignal is digitized, compressed and converted to IP packets and then transmitted over the IP network. Signaling protocols are used to set up and tear down cells, carry information required to locate users and negotiate capabilities.

Fax over IP (FOIP)


Currently, there are currently two ways to implement Fax over IP (FoIP). The first method is based on T.37 standard and is used mainly for store-and-forward faxing. It defines elements of how Internet email can be adapted to support a facsimile service and specifies the format in which fax is to be delivered as an e-mail attachment.
The second method is based on T.38 standard, a protocol for real-time delivery of FoIP. With T.38 real-time FoIP, faxes are delivered in real-time exactly like a regular fax call. Two fax machines should first establish a connection (synch up) and then send data over a local telephone connection, with an IP network between the two local connections. If the fax is busy, the caller gets a busy signal and the user has the option to retry sending later or to revert to store-and-forward mode as a transportation mechanism. A key point is that the confirmation takes place during the T.38 fax session, not at a later point.
The fax sent by a fax machine will be T.30 end to end. When that fax hits the IP subsystem of the phone, the MSP2020 subsystem of the IP phone (the hardware, the firmware and the software) will encapsulate the T.30 protocol data in the T.38 packets, which are then sent to the IP network through the Ethernet connection. At the other end, the IP phone will extract the T.30 protocol data from the T.38 packets. Thus, the fax call is T.30 end-to-end. This is different from G.711 pass-through, which is an option on many IP gateways, ATAs, and phones.
The current implementations for real-time FoIP via T.38 supports a maximum of V.17 (14.4Kbps) fax. An updated version of T.38 supports V.34 (33.6 Kbps) fax operations over IP has been standardized, but with no major implementations to date.

CDMA

Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. It should not be confused with the mobile phone standards called cdmaOne and CDMA2000 (which are often referred to as simply "CDMA"), that use CDMA as their underlying channel access methods.

One of the basic concepts in data communication is the idea of allowing several transmitters to send information simultaneously over a single communication channel. This allows several users to share a bandwidth of frequencies. This concept is called multiplexing. CDMA employs spread-sprectrum technology and a special coding scheme (where each transmitter is assigned a code) to allow multiple users to be multiplexed over the same physical channel. By contrast,time division multiple access (TDMA) divides access by time, while frequency division multiple access (FDMA) divides it by frequency. CDMA is a form of "spread sprectrum" signaling, since the modulated coded signal has a much higher data bandwidth than the data being communicated.

An analogy to the problem of multiple access is a room (channel) in which people wish to communicate with each other. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different directions (spatial division). In CDMA, they would speak different languages. People speaking the same language can understand each other, but not other people. Similarly, in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can understand each other.

WCDMA

WCDMA is a wideband spread-spectrum 3G mobile telecommunication air interface that utilizes code division multiple access (or CDMA the general multiplexing scheme, not to be confused with CDMA the standard). It provides simultaneous support for a wide range of services with different characteristics on a common 5MHz carrier.

The term WCDMA also refers to one of the International Telecommunications Union's IMT-2000 standards, a type of 3G cellular network. WCDMA is the technology behind the 3G UMTS standard and is closely allied with the 2G GSM standard. It provides new service capabilities, increased network capacity and reduced cost for voice and data services.

The term 'WCDMA Evolved' describes the evolution of WCDMA, addressing both operators' needs for efficiency and users' demands for enhanced experience and convenience. The first steps of this evolution are HSDPA and Enhanced Uplink.

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