[Asterisk-Users] Not ringing phone that are in use

[Derrick Shoemake]

We have a small number of phones, when a call comes in we want all the 
phones that aren't in use to ring.
Is there a simple way to test and see what phones are in use then ring 
the other phones? I tried some
code like this:

[zap]
exten => s,1,Answer
exten => s,2,ChanIsAvail(${DERRICK})
exten => s,3,SetVar,"EVERYONE=${DERRICK}"
exten => s,4,ChanIsAvail(${DON})
exten => s,5,SetVar,"EVERYONE=${EVERYONE}&${DON}"
...
exten => s,10,Dial(${EVERYONE},20)
exten => s,11,Voicemail,u200
exten => s,111,Voicemail,b200
exten => s,13,Hangup
exten => t,1,Hangup

Which caused Asterisk not to ring any phones or goto voicemail.

Here is the section of our extensions.conf :

DERRICK=SIP/202
DON=SIP/203
THOMAS=SIP/204
JAMES=SIP/205
BRUCE=SIP/206

EVERYONE=${DERRICK}&${DON}&${THOMAS}&${JAMES}&${BRUCE}

[zap]
exten => s,1,Answer
exten => s,2,Dial(${EVERYONE},20)
exten => s,3,Voicemail,u200
exten => s,103,Voicemail,b200
exten => s,5,Hangup
exten => t,1,Hangup