Internet telephony isn't a new technology —
it's been around for many years in one form or another, but only fairly recently
has it become reliable and ubiquitous enough to be a serious choice for
business. While Internet telephony was once an oddity often plagued for garbled
and dropped calls, these days a well-planned and implemented VoIP system can
provide call quality and reliability that rivals mobile phone or landline calls.
How VoIP Works
To understand how VoIP,
short for Voice over Internet Protocol,
works, it's helpful to compare it to how conventional phone calls operate. When
you place a "regular" phone call using the Public Switched Telephone
Network (PSTN), also known as Plain Old Telephone
Service (POTS) you use what's called
circuit-switched telephony.
This system works by setting up a dedicated channel (or circuit) between two
points for the duration of the call. These telephony systems are based on copper
wires carrying analog voice data over the dedicated circuits.
This is in contrast to newer Internet telephony
networks based on digital technologies. VoIP, in contrast to PSTN, uses what is
called packet-switched telephony. Using this system, the voice
information travels to its destination in countless individual network packets
across the Internet. This type of communication presents special
TCP/IP
challenges because the Internet wasn't really designed for the kind of real-time
communication a phone call represents.
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Key Terms To
Understanding VoIP:
Related Articles
on Webopedia:
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Individual packets may — and almost always do —
take different paths to the same place. It's not enough to simply get VoIP
packets to their destination. Yhey must arrive through a fairly narrow time window and
be assembled in the correct order to be intelligible to the recipient. VoIP
employs encoding schemes and
compression
technology (see G.7xx for more
information) to reduce the size of the voice packets so they can be
transmitted more efficiently.
PSTN Versus VoIP: A Feature Comparison
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PSTN |
VoIP |
- Dedicated Lines
- Each line is 64kbps (in
each direction)
- Features such as call
waiting, Caller ID and so on are usually available at an
extra cost
- Can be upgraded or
expanded with new equipment and line provisioning
- Long distance is usually
per minute or bundled minute subscription
- Hardwired landline
phones (those without an adapter) usually remain active
during power outage
- When placing a 911 call
it can be traced to your location
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- All channels carried
over one Internet connection
- Compression can result
in 10kbps (in each direction)
- Features such as call
waiting, Caller ID and so on are usually included free
with service
- Upgrades usually
requires only bandwidth and software upgrades
- Long distance is often
included in regular monthly price
- Lose power, lose phone
service without power backup in place
- 911 emergency calls
cannot always be traced to a specific geographic
location
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DID YOU KNOW...
How does one pronounce VoIP?
There are three popular ways to say it, with none being
a definitive "right" way. All are correct.
-
Some people will use the full acronym, pronouncing each
letter "V-O-I-P".
-
Some people will use use the first two words combined with
IP (pronounced as separate letters). This is actually more
like a phrase "Voice-Over-I-P".
-
Some will say the acronym as a word, just as it sounds (like
void only with a p at the end) "voyp".
To
avoid the situation completely, if you're not comfortable
using the term VoIP in a conversation, you can simply say.....
"Internet telephony". |
Parts of this article originally appeared on SmallBusinessComputing.com.
You can read the full version here in "VoIP:
A Primer for Small Business".
VoIP Meets WiFi
The advances of VoIP and Internet telephony in general have come a long way
since their inception. Most recently, the "next big thing" has been to merge
Wi-Fi with VoIP, producing one of the oddest acronyms you'll ever see. VoWiFi.
VoWiFi, or Voice over Wireless Fidelity, simply means a Wi-Fi based VoIP service
. or in even more general terms, a wireless based VoIP system.
The International Telecommunication Union
The International Telecommunication Union is an
international organization within which governments and the private sector
coordinate global telecom networks and services. This home page offers numerous
links to highlights and current topics, standardization, radiocommunication,
telecommunication, and general secretariat sectors.
Enterprise
VoIP Planet
The IT Manager's Guide to Voice over IP.
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