Emergency Ring Group To Group Conference

Here's a simple working example. There's enough there to get you started, just fill in some of the blanks. Let me know if you've got any questions.

Edit /etc/asterisk/extensions_custom.conf. Add the following where appropriate:

[from-internal-custom]
include => custom-alert
include => custom-alert-answer

[custom-alert]
exten => ctat,1,NoOp(Beginning alert IVR for ${CALLERID(num)})
;    list of users to call. FIRST number is where we dumb the alerted user into, SECOND is the caller ID, and all comma-separated entries after that are people getting alerted.
;    To be clear, you should change:
;    5000 to be your conference room or extension you want called
;    1000 to be the caller ID number users see on their phones
;    3456,4567 to be a comma-separated list of as many numbers as you want called
;  same => n,Set(anothergroup=5000,1000,3456,4567)
  same => n,Set(alertees=5560,${CALLERID(num),5067)
;    check that the caller is something local. dont rely on this.
  same => n,GosubIf(${LEN(${CALLERID(num)})}=4?ok:notok)
  same => n(ok),NoOp("Length checked out, continuing")
  same => n,GoSub(alertivr,1)
  same => n(notok),NoOp(Bad extension length (${LEN(${CALLERID(num)})}), hanging up..)
  same => n,Playback(goodbye)
  same => n,Hangup()

;    prompt for caller to enter password; you could have different alerts based on password entered if you wanted.
exten => alertivr,1,NoOp(Entering alert IVR)
  same => n,Background(enter-password)
  same => n,WaitExten(4)
  same => n,Hangup()

;    an example 'password'
exten => 1234,1,NoOp(${CALLERID(num)} entered the right password)
;    execute the call file script, passing in the variable with our alertees - this is what youd change with different 'passwords'
  same => n,System(/home/asterisk/alertfolks.sh ${alertees})
  same => n,Wait(1)
  same => n,Playback(goodbye)
  same => n,Hangup()

;    where the caller ends up; you could prompt them to accept the conference or whatever.
[custom-alert-answer]
exten => atan,1,NoOp(Alerting someone and dumping them in a conference)
  same => n,Playback(minneapolis&minnesota)
  same => n,Dial(Local/5560@from-internal)
  same => n,Hangup()

Create /home/asterisk/alertfolks.sh, include the following:

#!/bin/bash
#    template call file location
here="/home/asterisk"
callfile="alert.call"

#    what the alerted extension will be subbed for
alertext="%EXTEN%"

#    what the alerted destination will be (extension/conference/etc)
dest="%DEST%"

#    get arguments and put them in the ${extarr[@]} array
IFS=, read -ra extarr <<< "$@"

#    set the first element as the destination, second as CID, then discard them
destext=${extarr[0]}
fromext=${extarr[1]}
alertees=${extarr[@]:2}

#    loop through the alertees and build/move the call file
for i in $alertees; do
    cp $here/$callfile $here/$i-$callfile
    sed -i -e "s/$alertext/$i/g" $here/$i-$callfile
    sed -i -e "s/$dest/$destext/g" $here/$i-$callfile
    sed -i -e "s/$cid/$fromext/g" $here/$i-$callfile
    mv $here/$i-$callfile /var/spool/asterisk/outgoing
done

Create /home/asterisk/alert.call, include the following:

Channel: Local/%EXTEN%@from-internal
WaitTime: 8
MaxRetries: 2
RetryTime: 12
Callerid: %CID%
Context: custom-alert-answer
Extension: %DEST%

You can modify waittime/retrytime/maxretries as needed, obviously.

Set permissions on stuff, reload asterisk

chown asterisk. /home/asterisk/alert*
chmod +x /home/asterisk/alertfolks.sh
asterisk -rx 'dialplan reload'

At this point you should have a basic, working alert system. From here you can probably figure out how to schedule it, if you wanted to. All you need to do is change the list in extensions_custom.conf and you're set; the rest shouldn't need much/any touching (although you can do lots with just what i've given you).

If you have problems, please do the following from linux shell:

asterisk -rvvvvvvvvv
<reproduce issue>
exit

Copy resulting scrollback to pastebin.com, copy that link, paste it here.