The initial idea that telephony returns to is the POTS (plain old telephone service), technically called the PSTN (public switched telephone network). This system is being fiercely challenged by and to a great extent yielding to Voice over IP (VoIP) technology, which is also commonly referred to as IP Telephony and Internet Telephony.
Voice Over IP (VoIP) and Internet Telephony
These two terms are used interchangeably in most cases, but technically speaking, they are not quite the same thing. The three terms that personate one another are Voice over IP, IP Telephony, and Internet Telephony. They all refer to the channeling of voice calls and voice data through IP networks, namely LANs and the Internet. This way, existing facilities and resources that are already used for data transmission are harnessed, thereby eliminating the cost of expensive line dedication as is the case with the PSTN. The main advantage that VoIP brings to users is considerable cost-cutting. Calls are also often free. This along with the numerous advantages that VoIP brings has caused the latter to become a major technological element that has gained worldwide popularity and claimed the lion’s share of the telephony market. The term Computer Telephony has emerged with the advent of softphones, which are applications installed on a computer, mimicking a phone, using VoIP services on the Internet. Computer telephony has become very popular because most people use it for free.
Mobile Telephony
Who doesn’t carry telephony in their pocket nowadays? Mobile phones and handsets normally use mobile networks using the GSM (cellular) technology to allow you to make calls on the move. GSM calling is rather expensive, but VoIP has also invaded mobile phones, smartphones, pocket PCs and other handsets, allowing mobile users to make very cheap and sometimes free local and international calls. With mobile VoIP, Wi-Fi, and cellular technologies allow users to make completely free calls, even to overseas contacts.
Telephony Equipment and Requirements
What is required for telephony ranges between very simple hardware to complex equipment? Let us stay on the client-side (your side as a customer) so as to avoid the complexities of PBXs and servers and exchanges. For PSTN, you only need a phone set and a wall jack. With VoIP, the main requirement is a connection to either an IP network (e.g. an Ethernet or Wi-Fi, connection to a LAN), a broadband Internet connection and, in the case of mobile telephony, a wireless network connection like Wi-Fi, or cellular data. The equipment can then be as simple as a headset (for computer telephony). For those that want the convenience of the home phone without the computer, they need an ATA (also called a phone adapter) and a simple traditional phone. An IP phone is a special phone that includes the functionality of an ATA and many other features and therefore can work without depending on other hardware.
Not Only Voice
Since many media mix up on one channel, faxing and video conferencing also fall under the telephony banner. Faxing traditionally uses the phone line and phone numbers to transmit facsimile (shortened to fax) messages. IP Faxing uses IP networks and the Internet to send and receive fax messages. This gives many advantages but still faces certain challenges. Video conferencing works the same way as voice over IP with added real-time video.
