Busy extensions to play ivr

hello ,
i am new to asterisk,i have asterisk 1.8, i need to configure if the extension is busy, calls should go to an ivr ,
can this work
exten => 101,n(busy),ivr(testing),testing is an ivr which i have created.
if yes please let me know where should i put the code in /etc/asterisk/extensions.conf.

thanks in advance.

There is no “ivr” application in Asterisk 1.8. IVRs are contructed from lower level applications. There should be plenty of examples on the web.

You need a priority 1 line for extension, somewhere, and you willl need a line that runs Dial, which may or may not be the same.

I assume you want all failures to go to the IVR. If not, you will need to analyse the dial status and/or hangup cause, before going into the IVR code.