Busy Line not detected

Hi to all,

Change in my previous question. If possible then please share your valuable knowledge.

My problem is, how to find whether line busy or not. I already write down a code but its not detect the busy line. My extensions.conf are as follows

Quote:
exten => 1278,1,GotoIf($["${DIALSTATUS}" = "BUSY"]?5:2)
exten => 1278,2,Set(MYEXT=${EXTEN})
exten => 1278,3,AGI(My.php)
exten => 1278,4,Hangup()
exten => 1278,5,Busy
exten => 1278,6,Hangup()


When I establish a call from two different analog phone it's does not detect the line is busy. It's simply gives an engage tone.

So, My simple question is why it's doesn't detect whether line is busy or not?

Regards,
Deepen