Does Freeswitch support RFC 4662 for BLF Resource list URI?Asterisk does: https://wiki.asterisk.org/wiki/pages/viewpage. They have a good overview pageaction?pageId=30278158 Kamillio does: https://kamailio.org/docs/modules/3.2.x/modules_k/ rls.html Good info from Grandsteam about why to use this: http://www.grandstream.com/sites/default/files/ Resources/GXP21x0_Eventlist_ BLF_Guide.pdf Same with Polycom: http://community.polycom.com/polycom/ attachments/polycom/VoIP/ 19112/1/Technical%20Brief%20-% 20Busy%20Lamp%20Field.pdf Others have asked this question on the freeswitch users list, but responses were limited.