T26P - DSS Keys with BLF to external lines

[jolouis]

BLF is designed to monitor extensions. I'm not sure what Elastix does out of the box, but normal FreePBX/Asterisk installations do not generate the BLF hints needed to do what you are asking.

If you're familiar with dialplan code it's easy enough to add your own hints in to achieve what you want (i.e. be able to see if each line is in user or not). Keep in mind though that this is not a Key system... so you can't just go and call out on a specific line by pressing that button, or barge into a call that is running on that line when it's in use.

You should really look up Asterisk PBX vs Key system as it sounds like you are not familiar with some basic underlying differences.