VoIP Telephony Basic Guide

LAN Telephony

LAN telephony (sometimes called TeLANophy) use LAN systems to transport voice communications. LAN telephone technology is a merging of packetized voice with the high-speed data transmission ability of LAN systems. The ability to share data networks with voice systems offers significant cost reduction for telephone services.

LAN telephone system consists of LAN telephones, a data network, a LAN call processing system, and a voice gateway to the PSTN. LAN telephones convert audio into digitized packets that are transferred on the LAN to the call processing computer (CTI system). Each LAN telephone has its own network data address that is related to its telephone number or extension number.

LAN telephones can be integrated into computers or they can be standard along telephones that use LAN protocols that communicate with the systems. In 2001, there were several manufacturers producing IP telephones.

Introduction to IP Telephony

IP telephony is products and solutions to transport conversations over IP. You can use IP to create an all-in-one network to transport voice, video, and data. This infrastructure has many benefits such as cut-down administration, savings on telecoms expenses, and holistic messaging services. Voice and data traffic require two completely different solutions. Data traffic is can withstand and tolerate Wide Area Network links, lost packets, and intermittent packets. On the other hand, voice traffic cannot. It commands to receive packets in the same order as sent; if a packet is lost along the way, it will remain as such and may cause confusion at the receiving end.

Several components are required to have a successful IP Telephony set-up. They are LAN switch equipment, specialized routers, IP telephones, etc.

Conferencing and Transcoding, and Other Services

Conferencing allows multiple participants to communicate in a single call. There are two types of conferencing: ad-hoc and meet-me. In ad-hoc conferencing, the originating caller controls the conference, and determines who will be on the call. The participants may even continue the call after the originating caller hangs up. A meet-me conference allows participants to participate in a conference by calling an assigned number out of a pool of numbers. More participants can continue to join the conference call until the maximum number allowed is reached.

Transcoding is the process of converting IP packets of voice streams between a low bit-rate (LBR) CODEC to and from a G.711 CODEC. An LBR is a CODEC such as G.729a or G.723. An example of a need for transcoding is when a user across the IP WAN wants to access a voice mail system, which differs from the one he or she is communicating with. In which case, transcoding must be performed to convert the one to the other, in order to communicate with the voice mail system.

Call Transfer, Forwarding, Parking and Pick-up

IP phones support call transfer. By signaling back to the Call Manager (CM), a call can be transferred to the final destination. It can also be forwarded to a destination automatically, say when set to do so by default, or only in certain situations, say forwarding calls when busy or no answer. The call parking allows a person to receive a call at another telephone for privacy. A Park soft key allows the receiver to place the caller on hold and dial a designated extension number. At another phone, the extension number can be dialed to pick up the call. When answering an incoming call that is ringing at an unattended telephone, this feature is called call pick-up. Buttons or soft keys may be configured to activate this function.

Such are the basics of voIP telephony. Not much different from a local phone, but you'll notice the difference when your phone bill arrives: it has dropped significantly! Enjoy IP telephony and reap its benefits, today!