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What is CERNphone?

CERNphone is the softphone solution provided by IT department. It replaces CERN's legacy Skype for Business and Alcatel telephony services. CERNphone consists of a dedicated SIP backend, configuration and provisioning web interfaces as well as two phone applications:

  • CERNphone mobile: A mobile softphone app for iOS and Android customised to CERN needs (based on the popular Linphone open source VoIP client).
  • CERNphone desktop: A softphone app for Windows, macOS and Linux developed at CERN.

Recent presentations on CERNphone can be found here:

A CERN Bulletin article on the Skype for Business phaseout (end of June 2022) can be found here.

Why CERNphone?

There are several drivers behind CERNphone:

  • Focus on software based solutions replacing physical phones and avoiding associated costs (such as purchasing, installation and renewal of IP phones, networking switches and outlets, cabling)
  • Reduce costs originated by mobile calls - CERNphone calls are cheaper as handled by our fixed telephony operators, even when on data roaming
  • Use fixed telephony phone numbers owned by and reserved for CERN, rather than mobile numbers that may change again on future tenders.


  • Features of the service, as well as a comparison with Skype for Business, are found here.

Users and Numbers

  • All CERN classes of personnel and users that are authorised to obtain and use a CERN fixed telephony number can install and use CERNphone.
  • CERNphone offers two kind of numbers, for personal and for service usage.

Please consult this document for further information.

Migrating to CERNphone

Using CERNphone

Frequently Asked Questions

  • Find a list of FAQ's here.

Contact and support