Extension Monitoring (BLF)
From Snom Asterisk Portal
Contents |
Feature description
The snom phones ship with a row of free programmable soft-keys, which can be configured to monitor another extension of your VoIP network. The LED beside the button will blink when the extension on this button is ringing and will be steady on when the extension is in a call or unreachable.
You can even pickup a call for a ringing extension by pressing the extension button when the LED is blinking. See Call Pickup for a detailed explanation of the pickup feature.
Configure Asterisk
Monitoring a single extension
To enable the subscription and notification to extension events, you need to configure the special priority "hint" for every extension you want to monitor in the start context of your phone.
Presumed you have two extensions 21 and 22 with the start context "internal" configured in the sip.conf, a configuration example could look like the following.
extensions.conf
[internal]
exten => _XX,1,Dial(SIP/${EXTEN}) ; matches any 2-digit extension
[blf]
exten => 21,hint,SIP/21 ; monitors sip extension 21
exten => 22,hint,SIP/22 ; monitors sip extension 22
Note that you can monitor any other Asterisk technology like "Zap/g1", "IAX2/othermachine" with any (virtual) extension number.
sip.conf
[general] allowsubscribe=yes subscribecontext=blf notifyringing=yes notifyhold=yes limitonpeers=yes call-limit=99
Make sure you do not overwrite the subscribecontext option with a wrong context in a per-peer definition in your sip.conf. Notifyringing generates a lot of database transactions if you are using a realtime configuration database. It is set to "yes" in this example because it is neccessary for the Directed Call Pickup feature. The default in Asterisk for the shown options notifyringing, notifyhold and limitonpeers is "no" in Asterisk 1.4.
Monitoring multiple extensions
With the flexibility of Asterisks dialplan it is easy to monitor a group of extensions, even across multiple technologies. (ie. SIP, H323, Skinny, ISDN, ..)
extensions.conf
[internal]
include => blf ; includes content of context [blf]
exten => 20,1,Dial(SIP/21&SIP/22) ; if user dials 20 extension 21 and 22 will be called
exten => _XX,1,Dial(SIP/${EXTEN}) ; matches any 2-digit extension
[blf]
exten => 20,hint,SIP/21&SIP/22 ; monitors sip extension 21 and 22
Note that you can monitor any other Asterisk technology string like "Zap/g1", "Zap/23", "IAX2/foo" with any virtual extension number. (like "20" in the example)
Configure snom phones
snom 3xx
Firmware version <= 7.1.30
- Go to "Setup -> Function Keys" and configure a free function key for Button Type "Extension" and enter the Number of the extension you want to monitor. See this page for a detailed decription of the configuration of the free function keys.
Firmware version >= 7.1.33
- Go to "Setup -> Function Keys" and configure a free function key for Button Type "BLF" and enter the Number of the extension you want to monitor. See this page for a detailed decription of the configuration of the free function keys.
snom m3
The snom m3 handset does not support monitoring extensions or lines.
