I recently had to setup Remote BLF between systems for a customer with a mixture of FreePBX 15,16 and 17. They were all connected with pjsip trunks. Here is how a write up I did it and got it working. I have changed the names and IP addresses, and number of locations to protect the innocent. Previously I have configure IAX trunks for the calling and used pjsip for the device states, but this one used pjsip for both.
Great write-up, thank you!
Would you agree to it being posted on the wiki (some where near the https://sangomakb.atlassian.net/wiki/spaces/FCD/pages/10584435/Remote+BLF+s+using+PJSIP source page that you mentioned) ?