Call Flows is a application which allows you to create a phantom extension numbers, which will send calls to one of two destinations. The destination can be changed by dialling a feature code from any other real extension. This is most commonly used to create a day/night service feature, combined with a BLF key on a desk phone to indicate status.
To create a status key on a phone, create a BLF key with a value matching the feature code configured for the Call Flow.