Specifications
10
Next we tried Vitts. According to Vitts we were only 10.5K feet from the CO. As others have found out
DSL prequalification distance estimates are all over the place. The only way to get an accurate
measurement is to actually have the service installed. We were concerned the estimate might be too low,
but at least it gave us a chance to get the circuit installed. At worst we would have to settle for a lower
speed. We signed up for HomeReach 530 service. This is standard business SDSL 528kbp/s business
service with a relaxed service level agreement (SLA). SDSL requires a dedicated line. Vitts coordinated the
installation of a new line with Verizon. The service was installed and worked flawlessly until Vitts declared
bankruptcy and shutdown in May 2001 leaving us without high-speed access. Once again we were forced
to use dialup. Several other DSL providers service our area but deteriorating financial conditions made the
future look bleak.
Through DSL Reports I learned of Verizon presidential appeals, +1 888.216.1443. Did not hold out much
chance of ever getting DSL but called anyway. Less then four hours later all three phone lines were
qualified and ranked. I held off ordering for a while. At that time Verizon DSL had a pretty bad reputation
and they were changing acceptable use policy to restrict sending email. But I was getting desperate for
high-speed connectivity. Used DSL Reports to check local Verizon customers, got pretty good feedback
about the overall quality of service.
Ordered Verizon 1500/384 DSL in July 2001 with an activation date of early August. ADSL is different
then SDSL because it coexists with existing phone service. This reduces cost but requires a method of
separating DSL from phone signals. Verizon sends out a self-install kit that consists of special account
activation software, DSL modem and microfilters.
4.3 POTS/DSL Splitter vs Microfilters
ADSL requires a filter to isolate DSL from phone voice signals.
To reduce cost consumer grade DSL service typically use
Microfilters. This allows the customer to self-install DSL
eliminating the expense of a truck roll to dispatch a technician.
Microfilters must be installed on every non-DSL device.
An alternative to the microfilter is a single whole house
POTS/DSL splitter. This allows a single device to serve the entire
house. Splitters are especially valuable if you have a large
number of telephone devices or you are far from the telephone
central office. The splitter has better filter characteristics and
being installed at the NID does a very good job isolating inside
telephone wiring from DSL. A good way to see if a splitter will
improve DSL performance is to connect the DSL modem directly
to the Telco NID. This disconnects inside wiring. If performance
improves use a splitter.
The splitter includes half-ringer test circuit on the phone side of
the splitter. This allows the half-ringer in the NID to be
disconnected, further reducing unnecessary loads on DSL.
A single microfilter can be used to supply the entire house but a
purpose built POTS/DSP splitter has better filtering capabilities.
Advantage of Splitter
Single device for entire house
Better electrical characteristics
Isolates inside wiring from DSL
Isolates half-ringer test circuit from DSL
Works with Alarm installation
Figure 2 DSL Microfilter
Figure 3 POTS/DSL Splitter