adsl, Internet Access
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After many months of waiting Telkom have just announced
their ADSL product.As is always the case with these things, there seem to be more
questions than answers. For the moment we will answer as many
questions as we can. |
ADSL, technical details
ADSL is a technology for delivering data services,
(typically Internet Access) down the "last hop" of
the link from a telephone exchange to the user's
premises. Thus it is a replacement for dial-up
analogue modems and ISDN adapters.
It has the following features and limitations:
It is permanently connected. Ie you do not make and break
the circuit, as happens with normal dial-up links. You can
even talk on your phone while using ADSL, despite the fact
that both services share the same copper circuit.
There are no metered phone calls hence no call unit charges
It offers much faster bandwidth access than traditional
modems and ISDN lines.
It can only work over limited distances and not all local
exchange equipment and wiring will support the technology.
ADSL services for SA Internet Users
For years South Africans have had to live with the services
provided by our monopoly telephone company, Telkom. Both the
dial-up services and digital leased line services offered by
Telkom are very expensive in comparison to those available in
"first world" countries.ADSL, is also a monopoly service provided by Telkom. However it
is a new alternative to the above services, and for some users
it may provide significant advantages in price and performance.
The service can be broken down into components, some have to be
purchased from Telkom, while others may be purchased from other
ADSL service: The equipment to route data traffic over your
existing copper telephone circuit to a central point in your
exchange. This can only be supplied from Telkom. Costs for this
service are about R800 per month.
The ADSL "modem" device. This has to be purchased outright.
Like analogue modems and ISDN adpators, the
device should be approved by ICASA. Currently there is a
limited, ICASA approved range available from Telkom with prices
ranging from R2000 to R2500. However you are not obliged to
purchase from Telkom. Internet savvy South Africans may have
noticed that model range of modems and ISDN adaptors
on the local market seems much longer than published lists
of ICASA approved models. It is not clear whether this
situation will be allowed to develop with ADSL devices.
The Internet Access Service. This is the supply of Internet
bandwidth to the telephone exchanges, to be delivered to the
end user over the ADSL link. Telkom offer "ProLog" and
"ProLog Plus" services. However they are legally obliged to
allow other ISP's to offer competing services. Details of the
ADSL systems have only just been announced to competing
ISP's and none of them has yet announced a competing product.
Another option for the Internet Access Service will be services
supplied by Telkom but sold through "VISPs" (Virtual ISP's) like
ZSD. All the support and billing for these services will be provided
by the VISP.
What ADSL Related Services Will ZSD Offer
It is still early days, but ZSD is currently investigating the
Internet Access to ADSL customers supplied via the VISP route. All
support, billing and e-mail services will still be supplied by ZSD.
A version of our Zslic server to be coupled onto an ADSL line.
Services and products to assist customers with managing the
use of bandwidth on ADSL lines and providing security for their
How Good/Fast is ADSL?
ADSL has the potential to be MUCH faster than current
dial-up Internet services. However the limitation will not
be the speed of the ADSL link (which is rated at 512kbs) but
rather the speed of the upstream Internet access bandwidth. The
price of 512kbs bandwidth on a permanent link in S.A. is about
R40 000 per month. So at the price of the Telkom ProLog services
this bandwidth will have to be oversold nearly 200 times to cover
costs. The implication is you will not get full speed,
especially not on international links.The Internet Access Services currently offered by Telkom have
the following limitations:
Thus the ADSL service will not offer a direct alternative to
permanent "Diginet" links currently installed in many corporate
Individual end users have to "log in" with a user name and password.
Presumably they must also "log out" when they have finished, or
the system might do that for them.
A "dynamic" IP address will be assigned for every session. Thus the
service cannot be used to host web servers, to receive e-mail via
smtp or to facilitate remote access to customer networks.
There is a monthly limit of 3 GBytes of data.
Download speeds are not guaranteed.
How Soon Can I Get It?
That depends on where you live. Telkom has indicated that initially
the service will only be available in Gauteng. They have not
indicated when they will roll it out in Cape Town.Secondly it depends on how fast Telkom can install the
services. || || |
ZSD will be offering ADSL accounts via Telkom's VISP service.Currently only available in selected parts of Gauteng. Expected in
Cape Town from Easter 2003.
, Internet Access