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Advanced
How To Guide
Choosing
an ISP and a Telecommunication Method
ISDN
ISDN (Integrated Services Digital Network) involves
upgrading your existing phone line to a digital line
with two channels. It is generally considered the next
step for companies that have outgrown dial-up connections.
Eircom will carry out the work of upgrading your line
but your ISP may resell the service to you and project
manage the installation. For home and small office users
Eircom sells ISDN under the Hi-Speed brand name. Eircom
charges an upfront connection fee followed by a monthly
line rental. The usage charges for each channel are
the same as for a standard phone line. While the costs
are higher than with dial-up the increased speed of
connection means you can claw them back through more
productive use of the Internet .
The main advantage of ISDN is that the speed of transmission
to the Internet has increased. Each digital line can
operate at 64Kbits/sec. The basic ISDN offering, Basic
Rate Access (BRA), gives you two digital channels. The
two digital lines can be combined to give you a speed
of 128Kbits/sec, which is useful for transferring large
files but you will incur double phone charges. Alternatively
one line can be used for Internet access and the other
used for a telephone or fax line. Although upgrading
to ISDN may only take you from a connection speed of
56Kbits/sec to 64Kbits/sec you should see a marked improvement
in your connection speed as ISDN uses a digital line
rather than an analogue one. The ISDN does not need
to dial up: It is almost instantaneous access.
To upgrade to ISDN you will also need an ISDN modem
(also known as a terminal adapter) or router. An ISDN
modem is used when only one PC on your network will
be connecting to the Internet . An ISDN router or similar
solution will be used if more than one user on your
LAN requires email and Internet access.
To connect to the Internet using an ISDN line you will
need to get an ISDN account with your ISP. Charges for
this service vary, some ISPs provide it for free, others
charge a monthly or yearly fee. You should check with
your ISP whether they support 64Kbits/sec or 128Kbits/sec
access or both.
In addition to Basic Rate ISDN, Eircom also provides
Fractional Rate and Primary Rate ISDN, which offer more
digital channels. Primary Rate allows for up to 30 ISDN
channels and is usually used for video conferencing,
call centre applications or to provide remote access
to a corporate network for tele-workers. Fractional
Rate can deliver up to 16 channels.
Users [home or small office users] should be aware that
ISDN is a pay as you use service. It should be regularly
assessed against other 'lump sum' telecommunication
options, which are paid on a lump sum basis irrespective
of use [e.g. Leased Line or DSL]. A well known 'rule
of thumb' used by companies was that they should consider
replacing the ISDN option if they were using the line
more than 2 hours per day. Obviously, local prices for
the respective options would determine the applicability
of this rule of thumb.
DSL
DSL (Digital Subscriber Line) also involves upgrading
your existing phone line to a digital capability. It
offers higher speeds than ISDN and is expected to replace
ISDN over the next few years. DSL provides an always-on
connection to the Internet so you do not have to wait
for your modem to dial-up when you wish to connect to
the Internet .
DSL requires your local phone exchange to be upgraded.
DSL upgrades the current phone line but it can still
be used for voice calls while you are surfing the Internet .
There will be different DSL products available, from
those that are suitable for connecting a single PC,
to high-end products that will connect your entire LAN
to the Internet . It is expected that unlike ISDN, DSL
will involve a flat monthly fee for access.
DSL will not be available [initially at least] in rural
parts of the country. This is primarily due to the infrastructure
expense of providing this service. Accordingly, some
vendors are providing access to the Internet for these
rural areas via a satellite DSL service. This service
tends works very well for browsing the Internet and
for email. However, companies have experienced problems
with this service when transferring large files [e.g.
graphics] by FTP.
You may see references in the papers to ADSL, this is
simply one version of DSL.
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