Telephony replacement: analogue and critical lines

Addressing BT's removal of analogue telephone lines

BT is switching off analogue between January 2026 and January 2027.  To avoid the risk of service loss, all critical and analogue lines should be migrated from the existing Chorus telephony service to an alternative solution by the end of 2025. 

What are critical and analogue lines?

  • critical lines are telephone lines that serve critical services, such as lift phones, alarm lines, and backup lines for college lodges. They can be used for inbound and outbound phone calls and will continue to work in the event of power outages or disruption to the Chorus phone system.  They use dedicated copper wiring and network infrastructure, and have a Service Level Agreement (SLA) which means that outages should be responded to by our suppliers within 4 hours 
  • analogue lines are like critical lines and use the same network infrastructure. The difference is that they usually provide telephony to a legacy device which cannot be digital, and that service is not critical to life or business operations

What does this mean for my college or department?

The table below outlines the options available for replacement of analogue telephony lines.  If you need further guidance on these or about how to mitigate for different service outages, please contact the project team.

Microsoft Teams Phone

Teams Phone (also referred to as Telephony over Teams at the University) is part of the Microsoft Teams application and offers the user the ability to make and receive telephone calls through their Microsoft Teams client on any device. It also includes other functionality you would expect from a telephony service, for example the ability to transfer calls, receive or leave voicemail messages etc.

 

 

Existing line

 Solution
Analogue lift line

Via one of these options:  

  1. moving to GSM through  the Estates maintenance and modernisation contract  
  2. by individual colleges moving to GSM  
Analogue line (non-lift) that can move to Teams Phone without a handset   Move to Call Queue in Teams Phone
Analogue line (non-lift) in safety-critical location that can move to Teams Phone and requires handset (definition of safety-critical to be confirmed)  Poly handsets on Teams Phone
Analogue line (non-lift) that cannot be moved to handset e.g. alarm lines, electric meter lines, fax lines   Analogue Telephone Adaptor (ATA) to enable move to Teams Phone
Other analogue lines that cannot be moved to Teams Phone Upgrade analogue line associated equipment that is incompatible with new technology (e.g. an ageing alarm system)   

 

Critical and analogue lines not provided via Chorus

  • You will also need to review any analogue services that are not provided via Chorus.  This includes directly provided lines, which will not be covered by the Telephony Replacement project but will also need to be removed or replaced
  • We hold some records for directly provided BT lines and will provide support and advice where possible 

 Detailed information 

Expand All

Date Activity
April - July 2025 Proposal of alternative solution(s), migration process and schedule, cost model, support model and pricing information and briefing of appropriate bodies (for example, committees)
April - November 2025 Ascertain college and department numbers of analogue and critical lines moving to Teams Phone
April - November 2025 Post migration charging model shared for consultation
June - December 2025  Migration to Teams Phone or suitable alternative
August 2026 Post-migration charging model comes into effect

 

Please see the Telephony replacement distribution of costs webpage.

 

Further information about the service charging model will be shared when available. The service will be supported by the Communication and Collaboration Services Team in IT Services. IT Help webpages and Service Requests will be updated to reflect this over the coming months 

  • Collection of Chorus handsets from individuals and shared areas will be the responsibility of each individual college or department.  The project will coordinate and fund removal of handsets from college/department building(s) and their secure and safe disposal
  • The project will not fund the purchase of  headsets or Teams Phone compatible handsets for individual users nor handsets for shared area locations that are not safety-critical. However, it will fund shared area devices in safety-critical locations. 

NOTE:  Teams Phone can be used without a handset or headset through the computer's inbuilt speaker and microphone.

See indicative costs for Teams Phone compatible handsets on the IT Help website.

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