The ring cadence tells you the type of call alerting your phone:
ADDITIONAL INFORMATION:
Internal calls have a single ring cadence
External calls have a double ring cadence
To answer the call, pick up the handset.
ADDITIONAL INFORMATION:
If your phone rings for longer than a specified period (15 seconds in default), any re-direction feature that you have activated will come into effect. For example: call forwarding or voicemail.
