ACCOLC (Access Overload Control) was a procedure in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

for restricting

mobile telephone A mobile phone or cell phone is a portable telephone that allows users to make and receive calls over a radio frequency link while moving within a designated telephone service area, unlike fixed-location phones ( landline phones). This radio ...

usage in the event of emergencies. It is similar to the GTPS ( Government Telephone Preference Scheme) for

landline A landline is a physical telephone connection that uses metal wires or optical fiber from the subscriber's premises to the network, allowing multiple phones to operate simultaneously on the same phone number. It is also referred to as plain old ...

s. This scheme allowed the mobile telephone networks to restrict access in a specific area to registered numbers only and is normally invoked by the Police Incident Commander (although it can be invoked by the

Cabinet Office The Cabinet Office is a Departments of the Government of the United Kingdom, ministerial department of the Government of the United Kingdom. It is responsible for supporting the Prime Minister of the United Kingdom, prime minister and Cabinet ...

). The

emergency service Emergency services and rescue services are organizations that ensure public safety, security, and health by addressing and resolving different emergencies. Some of these agencies exist solely for addressing certain types of emergencies, while oth ...

s are responsible for registering their key numbers in advance. ACCOLC was replaced by MTPAS (Mobile Telecommunication Privileged Access Scheme) in 2009.

Purpose

The purpose of ACCOLC (US) was to restrict non-essential access to cellular phone networks during emergencies. This actively prevents unnecessary usage from congesting the cell networks, thus allowing emergency services personnel priority for communications. It also serves to control information flow in and out of a declared emergency area. Mobile networks can become overwhelmed by a high concentration of calls that often occur immediately after a major incident. Reliable access to the mobile networks, even during times when an exceptionally large number of calls are being made, is achieved by installing a special SIM (subscriber identity module) card in the telephone handset. Special SIMs are only available to entitled users within the emergency services community, and not to members of the public. Verizon Wireless in the United States has also implemented ACCOLC on its wireless networks, the modalities of use may differ from those in Britain especially with regards to ACCOLC being activated permanently on the network.

Implementation

In an emergency situation, the mobile network operator can implement ACCOLC onto specific mobile cell sites (that cover the area of the required restriction). Most systems allow the operator to allow/restrict specific Access Class levels to gain access to the cell sites. The customer's

SIM card A typical SIM card (mini-SIM with micro-SIM cutout)A SIM card or SIM (subscriber identity module) is an integrated circuit (IC) intended to securely store an international mobile subscriber identity (IMSI) number and its related key, which are u ...

is provisioned with an Access Class level between 0 and 15. Most SIM cards will be coded with a random access class level between 0 and 9. For special case mobile customers – e.g. emergency services, government officials, civil defence, etc. they will be issued with a SIM card with a high access class value (between 10 and 15). When the mobile operator needs to implement ACCOLC restriction, they will update the configuration on the specified cell sites. The access class value is a field that is transmitted in the broadcast channel of the cell. Under normal conditions, access class levels 0 – 15 are allowed. The SIM card compares what is allowed to its own access class level. If the allowed access class levels being broadcast by the cell site does not match what is on the SIM card, then the mobile device cannot access that cell – for any services.

Use

ACCOLC was deployed at the

Hillsborough disaster The Hillsborough disaster was a fatal crowd crush at a football match at Hillsborough Stadium in Sheffield, South Yorkshire, England, on 15 April 1989. It occurred during an FA Cup semi-final between Liverpool and Nottingham Forest in the tw ...

References

External links

London Assembly 7 July Review Committee Volume 4 Follow up report
Including report on ACCOLC being invoked around

Aldgate Aldgate () was a gate in the former defensive wall around the City of London. The gate gave its name to ''Aldgate High Street'', the first stretch of the A11 road, that takes that name as it passes through the ancient, extramural Portsoken ...

on 7 July by the

City of London Police The City of London Police is the territorial police force#United Kingdom, territorial police force responsible for law enforcement within the City of London, England, including the Middle Temple, Middle and Inner Temple, Inner Temples. The for ...

without reference to

GOLD Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...

control.
Introduction to Resilient Communications (Cabinet Office).
{{DEFAULTSORT:Accolc Emergency management in the United Kingdom History of telecommunications in the United Kingdom Mobile telecommunications standards

Purpose

Implementation

Use

See also

References

External links