Monday, August 13, 2012

How Does a VoIP Call Work?

VoIP telephony is in the process of displacing traditional landlines, include digital trunks such as T1 and ISDN PRI. What is it that is different about VoIP phone calls and what advantages does this technology offer?

Get options and pricing for telephone trunk lines and hosted VoIP phone services...You’ll hear VoIP referred to as a network service rather than a telephone service. This is an important distinction for network engineers and business owners, but not of much concern to users. One telephone set looks pretty much like another. When you lift the handset, you expect to hear dial tone and be able to dial out. When the phone rings, you expect to pick up the handset and hear the party on the other end and have a conversation.

A lot of engineering work has gone into making VoIP phone calls mimic traditional landline telephone calls as much as possible. The ideal has been that you shouldn’t be able to tell a difference. Now that this goal has been generally achieved, the new ideal is to make VoIP calls sound more lifelike than anything you’ve heard through a telephone. It’s something called HD or high definition voice.

The telephone connection is what determines whether you are using traditional telephony or VoIP. A traditional analog telephone line is based on technology that goes back over a century. It consists of two copper wires twisted together that connect a particular phone all the way to the telephone company office and into the central switching system. This line has certain AC and DC voltages and other characteristics. Often the phone line provides power to the telephone set. The phone itself has evolved from electromechanical components to relatively simple electronics. It just needs to have the proper characteristics to interface with the analog line.

This carries over to in-house telephone systems such as Key telephones or Private Branch Exchange (PBX). These are small switching systems that handle internal calls to keep them off the public telephone network. The in-house phone system connects to each phone in the company with a pair of wires that mimic the line from the phone company.

VoIP uses your company computer network as its phone line. For this to work, the phone has to include circuitry that makes it look like a network peripheral and be compatible with everything else on the network, including computers, printers, servers and so on. Phones that do this are called IP phones or SIP phones. They have a standard RJ-45 Ethernet jack on the back of the phone to connect to the network. They can be powered over this same connection by special POE (Power over Ethernet) switches or have separate plug-in power supplies to operate the internal electronics.

Smaller companies and residential users of VoIP can use regular telephone sets by plugging them into an ATA or Analog Telephone Adapter. This adapter has the electronics that you would find inside an IP Telephone.

VoIP gets its name from Voice over Internet Protocol. That doesn’t mean it has to run on the Internet, although some low cost VoIP services do use the Internet as your line to the service provider in order to save money. IP or Internet Protocol describes the technology used by Ethernet Local Area Networks. It’s what makes the Internet work and also runs many networks that don’t connect to the public Internet.

Actually, it’s easier to achieve high voice quality by avoiding the public Internet completely and connecting to your phone service provider through an extension of your network called a SIP Trunk. SIP (Session Initiation Protocol) is the switching technology for VoIP systems. The SIP Trunk takes the place of the analog, T1 or ISDN PRI telephone line that normally goes to the local telephone company.

You can set up a VoIP telephone system in your company that shares your computer network, including any WAN (Wide Area Network) connections between business locations. You’ll install a IP PBX to handle switching calls between office phones and connect to your service provider for outside lines. A newer option is to skip the IP PBX and rent Hosted PBX telephone switching from the same service provider that connects you to the public phone system. This saves a major investment and allows you to add more phones as you need them.

Are you considering installing a new business phone system or expanding or replacing one you already have? Get features and pricing for hosted PBX and telephone trunking optionsto help decide what makes the most sense for your company.

Click to check pricing and features or get support from a Telarus product specialist.

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