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Installation Preparations
4027620 Rev A 11
The maximum number of telephone devices connected to each RJ-11 port is limited
by the total Ringing Load of the telephone devices that are connected. Many
telephone devices are marked with a Ringer Equivalent Number (REN). Each
telephone port on the cable modem can support up to a 5 REN load.
The sum of the REN load on all of the telephone devices attached to each port must
not exceed 5 REN.
Telephone Device Types
You can use telephone devices that are not labeled with a REN number, but the
maximum number of attached telephone devices cannot be accurately calculated.
With telephone devices that are not labeled, each device should be connected and
the ring signal should be tested before adding more devices. If too many telephone
devices are attached and the ring signal can no longer be heard, telephone devices
should be removed until the ring signal works properly.
Telephones, fax machines, and other telephone devices use the center 2 pins of the
RJ-11 connectors to connect to your primary telephone service. The outer 2 pins of
the connector may be provisioned to provide a second telephone line. Contact your
service provider for more information.
Dialing Requirements
All your telephones should be set to use Dual-Tone Multi-Frequency (DTMF)
dialing. Pulse dialing may not be supported by your local service provider.
Telephone Wiring Requirements
The cable modem supports connecting to the interior telephone wiring as well as
connecting directly to a telephone or fax machine. The maximum distance from the
unit to the most distant telephone device must not exceed 1000 feet (300 meters). Use
26-gauge twisted-pair, or larger, telephone wiring.
Important: Connection to an existing or a new permanently installed home
telephone wiring network should be done by a qualified installer or at the direction
of your telephone service provider.
What Types of Service Accounts Do I Need?
Depending upon the features your service provider offers, you may need to establish
one or both of the following accounts:
A high-speed Internet access account, if your cable modem supports an Internet
connection
An account for telephone service, if your cable modem supports digital
telephone service