Line Keys, BLF, and Speed Dial — Configuring Phone Buttons
Line keys are the programmable buttons surrounding a desk phone's screen. Signal supports four key types — Account (a line for your own extension), BLF (a live status light for a coworker's extension), Speed Dial, and Park (a status light for a call-parking slot). Layouts are configured per-device in the portal and pushed to the phone.
What is BLF?
Busy Lamp Field (BLF) turns a key into presence for another extension: solid green when idle, red or fast-blinking when on a call, flashing when ringing. Pressing a BLF key calls that extension when idle — and during an active call, transfers the caller to it. On many models a flashing BLF can also pick up the ringing call. Receptionists typically run a page of BLF keys for the whole office.
Key types at a glance
Key type | What it does | Typical use |
|---|---|---|
Account | A line appearance of this phone's extension | Handling 2+ simultaneous calls |
BLF | Watches another extension; call/transfer/pickup | Front desk, assistants |
Speed Dial | One-touch dial of any number | Pharmacy, IT, key vendors |
Park | Watches a parking slot; press to park/retrieve | Any shared office |
Configure a layout
- Go to Devices → Phones, open the device, and select Line Keys.
- For each position, choose the key type, target value (extension, number, or park slot), and the label shown on screen.
- Save, then push Reload Configuration so the phone applies the layout.
Note: key counts differ by model (a VVX 400 has 12 positions; larger models and sidecar expansion modules add more — up to three sidecars per supported phone). Design one standard layout per role and copy it, rather than hand-crafting each phone.
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Last reviewed August 6, 2026. Still stuck? Contact Signal Support from your portal — include what you expected, what happened instead, and one example phone number or extension.