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Use of Multiple Appearance Directory Numbers (MADNs)

This policy defines a MADN, describes how location information impacts the ability of emergency services teams to respond, and documents Northwestern University's policy which has been enacted to facilitate identification of a 911 caller's location on campus.


Northwestern University students, faculty and staff.


During an emergency, response teams must be able to locate a caller in distress. When a phone number appears on two or more telephones, it could be difficult to identify the exact address, floor, and room from which a call was placed. This policy is intended to control the circumstances when multiple line appearances are permitted.

Policy Statement:

The installation of MADNs could effect E911 compliance and the ability of emergency response teams to locate a person in distress. Northwestern University strives to ensure the safety of students, faculty, employees, and visitors in campus buildings. To facilitate prompt response to E911 calls, the use of MADNs is limited to devices installed within a 100 foot radius, on the same floor. The following restrictions have been enacted to control the use of MADNs.

  1. At least one of the line appearances in a MADN group must appear on a single line phone (also known as “key 0”) or on key 1 of a multi-line set.
  2. MADNs can be installed anywhere within a house where University offices are located (e.g., 1922 Sheridan Rd).
  3. In most buildings (e.g., University Hall, Harris Hall, Leverone Hall), MADNs can be installed only in locations on the same floor.
  4. In buildings with multiple wings (e.g., Tech, Kresge Hall), MADNs can be installed in locations on the same floor within the same wing.
  5. MADNs cannot be installed across different buildings.


A Multiple Appearance Directory Number or MADN is a phone number that appears on two or more telephones. It may be on a single line phone, or on any key of a multi-line phone. A MADN is created when a user wants a phone number to appear on more than one telephone. Some examples of MADN applications include:

  1. Several phones ring at the same time when a number is dialed.
    (Ex: commonly used when several people are responsible for handling inbound calls to the same phone number so any available person can answer the call.)
  2. Visual indicator when a line is in use.
    (Ex: receptionist can see if someone is on the phone before transferring a call)
  3. Multiple phones in a room have the same phone number.
    (Ex: large lab)
  4. Calls to a phone number ring in multiple places.
    (Ex: faculty member has a lab and office on the same floor)
  5. Multiple phone numbers (two or more) appear on one phone.
    (Ex: administrative assistant has director's extension on phone, or receptionist phones have many other people's lines on their phone sets).


Enhanced 911 (E911) is an FCC regulation designed to ensure emergency services teams are able to locate a caller.
There are three key components of E911 which make it possible to automatically pinpoint the exact location of a 911 caller:

  • Public Safety Answering Point (PSAP) is a local (usually city or county) agency that answers 911 calls and routes them to emergency response teams such as police, fire, and/or ambulance services.
  • Automatic Number Identification (ANI) is a ten-digit number that is out-pulsed to the PSAP.
  • Automatic Location Identification (ALI) is a 20-character data record that is stored in a regional database. ALI is what defines the location of a 911 caller. In a high-rise, ALI describes an area within the building; for a campus environment, the description includes the floor and room location within a building.

When a person dials 911, the caller's phone number (ANI) is routed to the nearest PSAP. The ANI data is utilized by the regional ALI database to display the exact address and location of the caller.

Exceptions to this policy will only be granted upon the recommendation and written authorization from the offices of Information Technology, Risk Management, and the University Police.

Last Review Date:

December 2013

Original Issue Date:

January 2008

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