AT&T MERLIN LEGEND Release 3.0 Programming Summary Manual page 251

Remote Access Features
The Remote Access feature helps the customer, through proper
administration, to minimize the ability of unauthorized persons to gain access
to the network. Most commonly, phone numbers and codes are compromised
when overheard in a public location, through theft of a wallet or purse
containing access information, or through carelessness (writing codes on a
piece of paper and improperly discarding it). Additionally, hackers may use a
computer to dial an access code and then publish the information to other
hackers. Enormous charges can be run up quickly. It is the customer's
responsibility to take the appropriate steps to properly implement the features,
evaluate and administer the various restriction levels, protect access codes,
and distribute access codes only to individuals who have been fully advised
of the sensitive nature of the access information.
Common carriers are required by law to collect their tariffed charges. While
these charges are fraudulent charges made by persons with criminal intent,
applicable tariffs state that the customer of record is responsible for payment
of all long-distance or other network charges. AT&T cannot be responsible for
such charges and will not make any allowance or give any credit for charges
that result from unauthorized access.
To minimize the risk of unauthorized access to your communications system
follow these basic rules:
Use a nonpublished remote access number.
Assign barrier codes randomly to users on a need-to-have basis,
keeping a log of ALL authorized users and assigning one code to one
person.
Use random sequence barrier codes, which are less likely to be
broken.
Deactivate all unassigned codes promptly.
Ensure that remote access users are aware of their responsibility to
keep the telephone number and any barrier codes secure.
When possible, restrict the off-network capability of off-premises
callers using the Call Restrictions and Disallowed List capabilities.
System Features 15-29