The system administrator may restrict which keys you can configure. In most cases, you will only be allowed to configure unused and speed dial keys.
Multifunction Key 1 is always the primary line key for your extension number; Keys 2 and 3 on some models are always additional primary line keys. Line keys may be added contiguously with the same extension number, up to a maximum of four additional keys for each unique line key.
The default setting for a line key label is the extension number. Different extension numbers (from other provisioned extensions) may be assigned to other line keys, except key 1, which must always be your primary extension number. Multiple instances of the same extension number must always be contiguous and share the same label and ring tone settings.
Additional speed dial numbers can be set up in the Speed Dial Directory.