Voice over Internet Protocol Gateway, often mentioned only as VoIP gateway, is a hardware device used in the conversion of analog telephony traffic signal into digital packets data. The VoIP gateway arrange and encrypts this converted signal into packets of data and transmitted over an Internet Protocol(IP) network.

The article will introduce:

• What is a Voip Gateway?
• How does Voip gateway work?
• Voip gateway types
• How to choose Voip gateway?

What is a VoIP Gateway?

VoIP stands for Voice over Internet Protocol, which is a technology that allows you to make phone calls over the internet instead of using traditional telephone lines. With VoIP, your voice is converted into digital data that is transmitted over the internet, allowing for more efficient and cost-effective communication. VoIP offers a range of features and benefits, including lower costs, scalability, flexibility, and advanced calling features. By using a VoIP gateway, you can connect your VoIP system to traditional telephone networks, enabling you to make and receive calls to and from landline and mobile phones.

VoIP Gateway characteristics

The Voice over Internet Protocol (VoIP) gateway main characteristics includes:

• Signal control management;
• Packetization of data;
• Compression and decompression of fax and voice calls;
• Call routing;
• And interface of external controllers, such as network of management system, soft switches, gatekeepers or billing system.

How does a VoIP Gateway works?

VoIP gateway are uncomplicated devices, that simply works as a link between the Public Switched Telephone Network(PSTN) and the Internet Protocol(IP) network. By follow the origin of where the voice traffic signal arises from a VoIP gateway is able to convert the voice traffic signal into the appropriate form to be receive by the destination network, which can be PSTN or IP.

When the analog traffic signal originates from a PSTN, the VoIP gateway is bound to convert the analog traffic signal into a digital signal. By using a codec this digital signal is later on compressed and fragmented into packets of data that are transmitted over an Internet Protocol(IP)network utilizing a signaling protocol.

When the analog traffic signal originates from an Internet Protocol(IP) network, the VoIP gateway is bound to decompress the digital packets in a digital signal, and after that the signal is converted in an analog signal that is latter on sent by PSTN.

Protocols and codecs

The use of compatible protocols and codecs is indispensable for the good operation of the VoIP system and service, since it can play a big role in the call quality.

The protocols assures on how the voice packet is transferred between the network. The main VoIP protocols are: Session Initiation Protocol(SIP), which is the standard protocol utilized in most VoIP systems and services; Cisco Skinny Control Protocol (SCC),which is utilized in IP phones or Cisco’s Call Manager; Media Gateway Control Protocol (MGCP), which is the older VoIP protocol not longer utilized; and H.323, is also an old VoIP protocol, so it is also felt into disuse widely.

The codes assures the sound quality of the packet and it is in control of the compression of the voice stream in the digital packet. Usually a VoIP gateway is able to supports several codecs. The main codecs existing are: G.729(8kbps); GSM(13Kbps); iLBC(15Kbps); G.728(16kbps); G.726(16-24-40Kbps); G.722(48-56-64kbps); and G.711(64Kbps).

Types of VoIP Gateway

Initially is important to understand that there are two main types of VoIP gateways, that are the analog VoIP gateway and the digital VoIP gateway.

Analog VoIP Gateway

A analog VoIP gateway is utilized to make the connection between traditional analog telephones and VoIP phone system, or make the connection the VoIP phone system and the Public Switched Telephone Network(PSTN). Because of this two purpose of the analog VoIP gateway, this gateway has two different variations, that are the Foreign Exchange Office(FXO) and Foreign Exchange Subscriber(FXS).

FXO Gateway

FXO gateway is utilized to make the connection between the VoIP phone system and the Public Switched Telephone Network(PSTN) lines.

FXS Gateway

FXS gateway is utilized to make the connection between the usual telephones and fax machines and the VoIP phone system.

Digital VoIP Gateway

The digital VoIP gateway is utilized to make the connection between VoIP phones lines and the digital voice lines, like E1;T1;BRI. An digital gateway is also able to make the connection between traditional PBX system and Internet Protocol(IP) network.

Although the analog VoIP gateway and the digital VoIP gateway function similarities, this two gateways central difference is the interfaces used in each connection of there numerous solution components.

 Voice over Internet Protocol VoIP Gateway configurations

In the market you can find different types of VoIP gateways, in with also came with different configurations according to your need.

FXO Gateways are design with configurations of 4 ports, 8 ports , 16 ports , 24 ports and 48 ports.

FXS Gateways are design with configurations of 4 ports,8 ports ,16 ports , 24 pots and 48 ports.

Digital Gateways are design in 1T1,2T1,4T1;1E1,2E1,4E1;1BRI,2BRI and 4BRI.

What to take into consideration when purchasing a VoIP Gateway?

• Audio quality. The audio quality with lower traffic standard congestion must be near to the digital PBX, and Heavy traffic congestion must remain not far from the low.
• Device features and configuration. It is important to analyse the configuration and extra features design in the gateway, such as caller ID for identifying in the incoming caller, automatic number identification, and interactive voice response.