Installation Preparations

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

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Cisco Systems DPC3208, EPC3208 What Types of Service Accounts Do I Need?, Telephone Device Types, Dialing Requirements