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 Mass-market
telephony
A major development starting in 2004 has been the introduction of
mass-market VoIP services over broadband Internet access services, in
which subscribers make and receive calls as they would over the PSTN.
This requires an analog telephone adapter (ATA) to connect a telephone
to the broadband Internet connection. Full phone service VoIP phone
companies provide inbound and outbound calling with Direct Inbound
Dialing. Many offer unlimited calling to the U.S., and some to Canada
or selected countries in Europe or Asia as well, for a flat monthly
fee. One advantage of this is the ability to make and receive calls as
one would at home, anywhere in the world, at no extra cost. No
additional charges are incurred, as call diversion via the PSTN would,
and the called party does not have to pay for the call.
For example, if a subscriber with a home phone number in a U.S. area
code calls someone else in their home area code, it will be treated as
a local call regardless of where that person is in the world.
For the present, the broadband phone is likely to complement, rather
than replace, a PSTN line, due to a number of inconveniences compared
to traditional services. It still needs a power supply, and ready
access to a broadband Internet connection. Addidionally, a call to the
U.S. emergency services number 911 may not automatically be routed to
the nearest local emergency dispatch center, and would be of no use
for subscribers outside the U.S.
Another challenge for these services is the proper handling of
outgoing calls from fax machines, TiVo/ReplayTV boxes, satellite
television receivers, alarm systems, conventional modems or FAXmodems,
and other similar devices that depend on access to a voice-grade
telephone line for some or all of their functionality. At present,
these types of calls sometimes go through without any problems, but in
other cases they will not go through at all. And in some cases, this
equipment can be made to work over a VoIP connection if the sending
speed can be changed to a lower bits per second rate. If VoIP and
cellular substitution becomes very popular, some ancillary equipment
makers may be forced to redesign equipment, because it would no longer
be possible to assume a conventional voice-grade telephone line would
be available in almost all homes in North America and Western-Europe.
The TestYourVoIP website offers a free service to test the quality of
or diagnose an Internet connection by placing simulated VoIP calls
from any Java-enabled Web browser, or from any phone or VoIP device
capable of calling the PSTN network.
Corporate and telco use
Although few office environments and even fewer homes use a pure VoIP
infrastructure, telecommunications providers routinely use IP
telephony, often over a dedicated IP network, to connect switching
stations, converting voice signals to IP packets and back. The result
is a data-abstracted digital network which the provider can easily
upgrade and use for multiple purposes.
Corporate customer telephone support often use IP telephony
exclusively to take advantage of the data abstraction. The benefit of
using this technology is the need for only one class of circuit
connection and better bandwidth use. Companies can acquire their own
gateways to eliminate third-party costs, which is worthwhile in some
situations.
VoIP is widely employed by carriers, especially for international
telephone calls. It is commonly used to route traffic starting and
ending at conventional PSTN telephones.
Many telecommunications companies are looking at the IP Multimedia
Subsystem (IMS) which will merge Internet technologies with the mobile
world, using a pure VoIP infrastructure. It will enable them to
upgrade their existing systems while embracing Internet technologies
such as the Web, email, instant messaging, presence, and video
conferencing. It will also allow existing VoIP systems to interface
with the conventional PSTN and mobile phones.
Electronic Numbering (Enum) uses standard phone numbers (E.164), but
allows connections entirely over the Internet. If the other party uses
Enum, the only expense is the Internet connection
Use in Amateur Radio
Amateur radio has adopted VoIP by linking repeaters and users with
Echolink, IRLP, Dstar and EQSO. Echolink and IRLP are programs/systems
based upon the Speak Freely VoIP open source software. In fact,
Echolink allows users to connect to repeaters via their computer (over
the internet) rather than by using a radio. By using VoIP Amateur
Radio operators are able to create large repeater networks with
repeaters all over the world where operators can access the system
with actual ham radios. Ham Radio operators using radios are able to
tune to repeaters with VoIP capabilities and use DTMF buttons to
command the repeater to connect to various other repeaters, thus
allowing them to talk to people all around the world, however powerful
their radio. |
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