Xerox WorkCentre Pro 421 User Manual page 207

The REN is useful to determine the quantity of devices you
may connect to your telephone line and still have all of those
devices ring when your number is called. In most, but not all
areas, the sum of the RENs of all devices should not exceed
five (5.0). To be certain of the number of devices you may
connect to your line, as determined by the REN, you should call
your local telephone company to determine the maximum REN
for your calling area.
WARNING:Ask your local telephone company for the
modular jack type installed on your line. Connecting this
machine to an unauthorized jack can severely damage
telephone company equipment. You, not Xerox, assume
all responsibility and/or liability for any damage caused
by the connection of this machine to an unauthorized
jack.
You may safely connect the machine to the following standard
modular jack: USOC RJ-11C. Use the standard line cord (with
modular plugs) provided with the installation kit to connect it.
An FCC compliant telephone cord and modular plug is
provided with this equipment. This equipment is designed to be
connected to the telephone network or premises wiring using a
compatible modular jack which is Part 68 compliant.
Do not connect this machine to a party or coin operated phone
line.
Repairs to the machine should be made only by a Xerox
representative or an authorized Xerox service agency. This
applies at any time during or after the service warranty period.
If unauthorized repair is performed, the remainder of the
warranty period is null and void.
If you find the telephone line is damaged or the telephone
company notifies you that your machine is causing damage,
disconnect the machine from the telephone line and call for
service. Do not reconnect the machine until necessary repairs
are made.
WorkCentre Pro 421 User Guide A-11