1. In order to setup the BLF keys, you will need to know the full extension number, which includes your service identifier prefix. For example, extension 101's full extension number may be 111101.
If you have access to the My Account Portal, you can find the full extension number by clicking edit on any of your extensions in the PBX Extensions page. If not, you can find this on your handset by holding down the Line key. This will normally be the top left hand line. The phone will show you a prompt containing your full extension number. Split the extension number into the two parts, service id + extension number, and remember the service id. For example, if your extension is 101, and your full extension number is 4214101 (4214+101), remember 4214
2. Hold down one of the unconfigured line keys on your handset, that you wish to use to monitor another extension. When the Key configuration prompt appears, enter BLF as the key type, then enter the full extension number of the extension you'd like to monitor. If this was 103, and your service ID from the previous step was 4214, you would enter 4214103. Enter the name you'd like this key to display as on your phone screen (for example, the person's name), then push the Save key.
3. Repeat this for any other line keys you would like to configure, remembering to change the extension number to the correct person for each key.