To know when the specified user phone is ringing, BLF is needed to blink red on the button when user phone is ringing, steps to be done as following:
- Use an administrator account to log in to the web management system of a U1900 series unified gateway.
- On the or page, select the user number to be assigned the service permission and click Service Configuration.
- Under Simple service, select the service to activate and click OK.
- In the upper right corner of the web page, click
to save the configuration - Under Complex service, click Configure next to IP phone status detection.
- Set Activate to Yes, set Message push to On, and click OK.

Log in to the web management system of the IP phone
Choose and set Busy Lamp Field to Authorized.
Click Save
In the web management system of the IP phone, choose .
Click a programmable button on the right. In the window that is displayed, configure the Pickup and select BLF
