Desk phone registers but BLF lights never update

Scenario

Phones can call normally, but busy lamp field indicators stay stale or blank after provisioning.

Recommended Resolution Path

1. Check PBX feature licensing and whether the subscription list is too large for the handset.
2. Review provisioning templates and firmware for the affected model.
3. Compare one working extension with one failing extension at the SIP level.
4. Document template changes because phone features are easy to break globally.

Technician Notes

Document what changed, what confirmed the fix, and whether the issue points to a broader standards gap worth addressing for the client.