What is VoIP
Voice over Internet Protocol (VoIP) is a term used to describe the transmission technologies for delivery of voice communications over Internet protocol (IP) networks such as the Internet. Other terms frequently encountered and synonymous with VoIP are IP telephony, Internet telephony, voice over broadband, broadband telephony, and broadband phone.
Internet telephony refers to communications services -voice, facsimile, and/or voice-messaging applications—that are transported via the Internet, rather than the public switched telephone network (PSTN).
Companies that offer VoIP services include:
The basic steps involved in originating an Internet telephone call are conversion of the analog voice signal to digital format and compression of the signal into internet protocol packets for transmission over the Internet; the process is reversed at the receiving end.
VoIP systems control the set-up and break-down of calls and use audio codecs which encode speech allowing transmission over an IP network.
There are three common methods of connecting to VoIP service providers:
- An analog telephone adapter (ATA) can be connected between an IP network (such as a broadband connection) and an existing telephone jack.
- A dedicated VoIP phone that connects directly to the IP network and uses technologies such as Wi-Fi or Ethernet.
- An Internet phone or Digital phone – software that can be installed on a computer that allows VoIP calling without dedicated hardware.
Reservations about adopting VoIP service.
- IP networks can be unreliable compared to the circuit-switched public telephone network, and does not inherently provide a mechanism to ensure that data packets are delivered in sequential order, or provide quality of service guarantees.
- Voice and data packets travel over the same network and the system is more prone to congestion and denial of service attacks.
- IP phones and VoIP telephone adapters which connect to routers or cable modems typically depend on the availability of electricity which make them susceptible to power outages.
- Emergency calls cannot easily be routed to a nearby call center because the nature of IP makes it difficult to locate network users geographically.
- Since it is a computer-based technology, Voice over Internet Protocol telephone systems are as susceptible to attacks as PCs.
- Routing VoIP traffic through firewalls and network address translators can be a problem.
- Some VoIP solutions do not support encryption, so, it is relatively easy to eavesdrop on VoIP calls and even change their content.
- Some VoIP providers may allow a caller to fake the caller ID information, potentially making calls appear as though they are from a number that does not belong to the caller.
- The ability to send faxes over VoIP may be limited.
10. Another challenge for VoIP implementations is the proper handling of outgoing calls from other telephony devices such as DVR’s, satellite television receivers, alarm systems, and other similar devices.
- ^ “Voice over Internet Protocol. Definition and Overview”. International Engineering Consortium. 2007. http://www.iec.org/online/tutorials/int_tele/index.asp..