What is a voice over IP line?

Sending voice over the internet

Since the advent of internet telephony, many residential offerings have evolved to compete with traditional local and long distance telephone service providers. These services save households money by using the public internet to bypass traditional local loops and long distance lines. They send voice calls by converting analog signals into digital packets that travel over the internet. This type of transmission uses Voice over Internet Protocol or Voice over IP (VoIP). The packets are then re-combined at their destination back into voice so that you can converse with your called party.

Common VoIP services in use today

Analog Telephone Adapter (ATA) - An analog telephone adapter (ATA) allows you to connect a standard telephone to the Internet. It essentially converts analog signals from your traditional phone into digital data packets to transmit over the Internet. ATAs are simple to use, easy to set up, inexpensive, and are a great alternative to traditional home phone lines. Many major VoIP providers like Vonage supply ATAs for free when you sign up for their services.

Computer-to-Computer - Using VoIP to make calls from computer to computer was the earliest form of internet telephony. You just need the software, a headset with microphone or speakers with a microphone, a sound card, and a good internet connection. Typically there is no charge to make PC to PC calls, and the software can even be downloaded for free. Common services include Skype and Yahoo! Messenger.

Hosted IP Phone Service - Hosted IP phone services use a central IP softswitch that IP telephones connect to over the internet. IP phones have the same appearance as normal telephones, but instead of having a traditional phone jack, they have an Ethernet connector. These phones connect directly to your Internet router and contain all of the necessary technology to directly handle the IP phone call; no conversion from analog to digital is necessary. The hosted provider provisions the IP phones to connect to their IP softswitch so that they can route your voice calls over the internet to your called party.

How do businesses take advantage of VoIP?

Some businesses subscribe to VoIP services through providers like Vonage or local cable companies. By connecting the analog line ports of their current phone system directly to the VoIP service providers ATA or analog gateways, businesses can convert their calls to VoIP and save on local and long distance charges. These services disconnect your phone system from the public switched telephone network (PSTN) and connect it to the provider's IP network for call routing over the internet.

Another popular business VoIP service that is rapidly developing is SIP trunking. Session Initiation Protocol (SIP) is a protocol used to for controlling multimedia communication sessions such as voice and video calls over the internet. SIP trunking is offered by Internet Telephony Service Providers (ITSP). By using a SIP trunk, you disconnect your IP PBX from the PSTN and connect it to the ITSP's IP network. This network is connected to other private IP networks, the public internet, and the PSTN. The ITSP will determine if your call is being made to a PSTN number or to another SIP enabled phone system. It will then route your call through the Internet to wherever it is directed.

Because a single SIP trunk can handle many channels (voice conversations), it can process as many calls as traditional digital services. SIP trunks have the potential of being a cheaper alternative to both analog telephone lines and T1/PRI.

Voice quality considerations

Although quality of service is still a hot topic, the quality of today's VoIP connections are quite good. If you've used a VoIP softphone like Skype or Yahoo! Messenger then you may have experienced issues like echo, latency (delayed speech), and diminished sound quality. These problems are much less apparent on private IP networks but can arise when the voice packets are traversing the public internet. The best providers have large private IP networks and usually provide better quality than providers that use the public internet for most voice travel.

Can my phone system handle VoIP lines?

Any PBX that can handle analog telephone lines can be equipped with VoIP services that use ATAs or analog gateways. The VoIP service is connected to the ATA, and the line is connected directly to your PBX. SIP trunks are compatible with IP PBXs that support SIP trunking. Most current IP PBX offerings support SIP trunks and typically require licensing to activate this feature.

When should I consider ordering VoIP lines?

VoIP lines can be a substitute for both analog telephone lines and digital T1/PRI services. The choice usually involves cost and features, but quality of service should never be ignored. If your lines go down even for a few hours, the savings of switching services may be lost. It is best to research your provider's reviews on the internet and contact current users of the service.