Monthly Archives: September 2011

Filtering calls with Asterisk

I mentioned on Google+ that I get Asterisk to filter my calls during times when it’s inconvenient to answer the phone and someone asked me to post the details. I’m definitely not an Asterisk expert so there’s probably a better way of doing this.

The PSTN line is answered through a SPA3102 and it is configured not to automatically make the phone on the FXS port ring on incoming calls. There is an option in the advanced settings on the PSTN Line tab on the SPA3102 web config interface that allows you to do this:

Ring Thru Line 1: No

The means that the phone on the FXS port does not ring at all unless the call gets through the filtering in Asterisk and Asterisk tells it to ring.

Below is the relevant excerpt from the extensions.conf file.

; Whitelist various phone numbers
exten => s,n,GotoIf($["${CALLERID(number)}" = "0403XXXXXX"]?ring-all-phones,s,1)

; Check to see if we want to block all calls currently
exten => s,n,GotoIf($[${DB(phonecontrol/state)} = "block"]?out_of_hours,1)

; Check to see if its the right time period to accept calls
exten => s,n,GotoIfTime(9:00-23:00|mon-fri|*|*?ring-all-phones,s,1)
exten => s,n,GotoIfTime(11:00-21:00|sat-sun|*|*?ring-all-phones,s,1)

; Check to see if we want to accept all calls regardless of the time
exten => s,n,GotoIf($[${DB(phonecontrol/state)} = "accept"]?ring-all-phones,s,1)

exten => s,n,Goto(out_of_hours,1)

; Message about not accepting calls
exten => out_of_hours,1,Background(custom/out_of_hours)
exten => out_of_hours,n,WaitExten(5)
exten => out_of_hours,n,Goto(1)

; Ring phone anyway (1)
exten => 1,1,Goto(ring-all-phones,s,1)

; Leave voicemail (2)
exten => 2,1,VoiceMail(3000@default,u)
exten => 2,n,Hangup

The DB entry for phonecontrol/state which is controls whether or not I want to override whether calls are accepted or not is toggled through a web interface.