| A Voice over Internet Protocol, or VoIP, transmission is | | | | A dialup hard phone is one with a built-in modem |
| initiated by converting voice into digital format. This can | | | | instead of an Ethernet port. A wifi hard phone is built |
| be done by Analog Telephone Adaptor (ATA) or by | | | | with a wifi transceiver to connect to a wifi base |
| the computer itself using software. In the Public Switch | | | | station to be connected to a remote VoIP server. This |
| Transmission Network (PSTN), the dialing of the | | | | can be used to transfer calls to a GSM network. |
| number initiates the call by connecting the call to the | | | | A soft phone is run by software in the computer. This |
| public switch and routing the call to the correct party's | | | | requires appropriate hardware such as a microphone, |
| telephone number through the telephone network. | | | | a speaker or a USB port. Once dialed, the phone |
| A VoIP network also has similar functions like that of | | | | number is processed by the call processor, which is |
| PSTN, in addition to the IP provider and Internet | | | | actually hardware running a database mapping |
| Service Provider (ISP). The major components of a | | | | program called soft switch; the software manages all |
| VoIP network are user devices (one or both ends), a | | | | connections. This is also called IP PBX (private branch |
| call processing server, VoIP gateways, gatekeepers | | | | exchange), similar to the PBX of the PSTN lines. |
| and an IP network. The user device consists of VoIP | | | | There are gateways and gatekeepers that control the |
| phones, traditional phones with accessories and | | | | call admission and bandwidth management. They also |
| computer-based devices. VoIP phones may be hard | | | | control the creation of IP packets that contain the |
| or soft phones. | | | | voice data and other information about the call. |
| A VoIP hard phone is like a traditional phone, but | | | | Finally, there is the IP network, which consists of |
| instead of a phone jack, it has an Ethernet port | | | | distributed routers ensuring connectivity. This IP logical |
| through which it communicates directly with a VoIP | | | | switch is referred to as the soft-switch architecture. |
| server or another VoIP phone. It doesn't need a | | | | These four components form the phone system for |
| personal computer, only an internet connection. These | | | | VoIP, in addition to the software and various protocols |
| hard phones may also come cordless. | | | | through which the call is smoothly communicated. |