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BLF with 8851-3PCC on Asterisk System

Level 1
Level 1

Hi Together,


i'm having problems with configuring BLF on 8851 3PCC with Asterik System. BLF are blinking and when pressed i've getting failure "Invalid Number".


Software Version: sip88xx.11-0-1MPP-477.loads

Voice with no problems, Calls possible

Voice configured under Ext 1:

Proxy/Outbound Proxy:

Display Name: Test 125

User ID 12345mv125

Auth ID: 12345mv125

Extension Number: 125

Extension Number from User, who should be on BLF: 124


Configuration of line keys:

Line Key disable, Sahre Call Appearance private, Short Name $USER,

Extended Function: fnc=blf+sd+cp;sub=124@$PROXY;usr=124

Other tested "Extended Function": 

* fnc=blf+sd+cp;sub=12345mv125;usr=124

* fnc=blf+sd+cp;;usr=124

* fnc=blf+sd+cp;;


I used this Admin-Guide for make configuration:


Step 1   On the Configuration Utility page, select Admin Login > Advanced > Voice > Attendent Console.
Step 2   Select a key expansion module line key.
Step 3   Enter a string in this format:



  • fnc= blf means function=busy lamp field
  • sub= the subscribing phone, the phone that monitors the status of other phones with busy lamp field. This name must be identical to the name defined in the List URI: sip: parameter. xxxx is the name that is defined in List URI: sip: parameter. Replace xxxx with the exact defined name. $PROXY is the server. Replace $PROXY with the server address or name.
  • usr= the BroadSoft user being monitored by BLF with 8888 as the phone being monitored. Replace 8888 with the exact number of the monitored phone. $PROXY is the server. Replace $PROXY with the server address or name.
Step 4   (Optional) To enable the busy lamp field to work with speed dial or call pickup, enter a string in the following format in the Extended Function field: Extended Function field, enter a string in this format:



sd= speed dial

cp= call pickup

Step 5   Click Submit All Changes.


Anyone who could help me?




2 Replies 2

Level 1
Level 1

I know this is old, but it comes up on searches for this topic. 


Where 102 is the Sales extension. This is working on a 8841-3PCC
Connected to FreePBX

@dmessano21  did you have to install or set up anything custom in asterisk to get the blf to work or does that work out of the box. For me the BLF lamp stays solid green doesn't seem to receive any hints from asterisk.


Asterisk 13.38.2

PBX Version:
Product Name: CP-8861-3PCC
Software Version: sip88xx.12-0-4MPP0101-205.loads