How Do IP Phone Systems Work?

IP phone systems are gaining immense popularity among companies all over the globe. They have become an essential tool for communication both within and outside an organization. An IP phone system transmits data over IP (Internet Protocol) layer and is referred to as VoIP technology.


IP phone system uses a set of technologies to deliver multimedia sessions and voice communications over Internet Protocol (IP) networks. It is a combination of software and hardware which transmits voice signals in the form of data packets using Internet Protocol and packet switching.


IP phone systems are built on what is called an IP-PBX. The IP-PBX gets connected to the Internet on one end and to the router or switch for connection to end devices on the other. All voice calls start from one IP address and goes on to another IP address. The IP-PBX identifies the caller and called person’s ID and matches it to their corresponding IP addresses. When a caller initiates a call, the IP-PBX locates the called person’s IP address, connects the two and steps back.

Analog-Digital Conversion

At the end device level, the IP-Phone converts the voice signal into data packets through a built in analog to digital converter (ADC). Similarly, it converts incoming data packets into voice signals to be heard on the IP Phone using a digital to analog converter (DAC). Other than this one instance, voice signals travel through the Internet as regular data packets very similar to your email or data exchange.

IP phone systems are scalable and numerous users can be connected on the same network. These phone systems are loaded with the most advanced telephony features that fulfill modern communication needs.

Internet Protocols

IP-based phone system uses multiple control protocols like Skinny Client Control Protocol (SCCP), and Session Initiation Protocol (SIP). SIP offers many functions such as negotiating the codec used during calling, transferring of calls, and terminating the calls.

End Devices

An end device is usually an IP phone that allows one to take a standard phone voice signal, and convert it into digital packets which can be transmitted over the Internet. IP phones are special type of phones which look almost like normal phones but have RJ-45 Ethernet connector instead of RJ-11 connectors. These phones can connect directly to the router and have all the necessary software and hardware to handle IP calling. In case of peer to peer calls, IP phones communicate directly over the Internet and stream audio directly. Analog and cellular phones cannot use peer to peer and SIP.

SIP Trunking

Many IP based business phone systems use IP-PBX and SIP trunking to create a bridge between PSTN and IP digital circuitry. By routing audio signals from the IP phone through IP-PBX and PSTN, it is possible for IP phone to establish call with cellular or analog land-line phones.

The IP phone system connected to the Internet has specific IP address assigned to it. Each time a phone engages an IP call, its IP address is decoded into the phone number which is then handed to the network. At the VoIP level, a phone may identify itself with an SIP registrar by showing it’s account credentials.

Packet Switching

IP phone does not use circuit switching technology. Instead of routing data over a dedicated line, the packets of data flow through a network along multiple possible paths. This is known as packet switching and opens a brief connection which is just long enough for sending a chunk of data known as a packet from one system to another. Whenever a call is made from the IP phone system, the user ID and IP address of the called person are identified, and when they match, the call gets connected.


IP communication technology enables device mobility. A residential broadband connection can be used as link to a VPN (Virtual Private Network) of an organization which enables voice data transmission.

An IP phone system is not restricted to any particular area or location. This results in excellent mobility options. IP Phones can be easily shifted from one place to another without much effort. Again, one can make calls from anywhere as long as the phone is under IP network coverage.

Most of the businesses use IP phone systems through their managed private network rather than public Internet as private network ensures security. An IP phone on private network also provides better control of the system as well as service quality. Thus, we get to see that IP phone systems offer better management over all your communication usage.

About BCS Consultants

BCS Consultants offers complete range of products and services for networking and communications. In communication we offer on-premise systems from companies such as Toshiba, private cloud based IP, and public cloud based IP Phone systems.

Call us today on (949) 333-1020 for your networking or communication needs.

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