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CERNphone features

Available clients

  • Desktop client
    • Windows
    • Mac
    • Linux
  • Mobile client (CERN and private smartphones)
    • iOS
    • Android
  • IP Phones (for justified use cases)

The same telephone number can be registered and used in several clients. For the mobile client, up to 3 mobile devices can be configured with the same number.

All clients registered for the same number will be able to simultaneously place/receive calls.

Telephony features

  • Basic telephony features:
    • Place/receive calls to/from CERN and any external phone number.
    • Call transfers.
    • Ad-hoc 3-party conference.
    • Call park and retrieve.
    • Music on hold.
    • Call log.
    • Trusted caller name presentation for calls within CERN.
  • Multi-line (ability to handle several calls simultaneously).
  • Voicemail and missed-calls via e-mail.
  • Configurable call forwarding and simultaneous ringing for CERN numbers via the CERNphone User Portal.
  • Configurable calendar-based call forwarding.
  • Configurable do not disturb (DND).
  • Telephony spam filter:
    • Spam call filter for incoming calls (operators & CERN blacklist).
    • Personal spam filter / blacklist (on demand).
  • Support for shared numbers:
    • service numbers,
    • configurable group call pickup (parallel/sequential/circular ringing),
    • configurable group call forwarding.
  • Encrypted communications (signalling and media).
  • High-Definition audio quality for intra-CERNphone calls.


  • Support for team members (people that can receive calls on behalf of another number).
  • Support for delegates (people that can place calls on behalf of another number)
  • CERN address book integration.
  • Local contacts.
  • Contacts' presence via CERN calendar integration and CERNPhone status (on call, DND, free) for Desktop client and IP phones.
  • Integration with Mattermost for chat:
    • Launching a Mattermost chat from the CERNphone desktop app.
    • Launching a CERNphone desktop call from Mattermost.
  • Desktop client configurable as default app for calls.


  • There is no cost to install the clients nor to use the service.
  • Calls to non-CERN numbers are billed by our telecom operators, however, its price is much cheaper than calls placed directly from your mobile subscription (a factor of 100 for calls to the USA as example).
  • Long-term savings to the Organization thanks to low infrastructure costs (fixed telephones, cabling, network components) and no licensing costs (based on Open-Source components).

Numbering plan

  • Unique number (+412276xxxxx) for all communications (desktop and mobile clients) independently of your location.
  • Future-proof numbering scheme (CERN-managed +412276 number range), contrary to mobile GSM numbers that may change in the future.


  • Redundant back-end service on-premises.
  • Based on open standards.
  • Desktop and mobile client can connect via Wi-Fi and mobile networks, providing world-wide availability via your CERN fixed number.
  • Low data consumption (less than 1MB per minute) for cost-efficient communications when on mobile networks.
  • Minimal battery consumption thanks to app wake-ups via Push Notifications.
  • In-call network handover support (resilient to network changes).
  • Integration with CERN's fixed-telephony external operators.

Advanced features

  • Automatic Switchboard (auto-attendant).
  • Call centers.
  • Recording service.
  • Integration with third party systems (access control, emergency phones, TETRA, lifts, etc.).