[a2billing]
exten => _X.,1,GotoIf($["${EXTEN}" = "6245"]? 6) 
exten => _X.,2,GotoIf($["${EXTEN}" = "150"]? 7) 
exten => _X.,3,GotoIf($["${EXTEN}" = "867"]? 8) 
exten => _X.,4,DeadAGI(a2billing.php|1)
exten => _X.,5,Hangup
exten => _X.,6,VoiceMailMain(${CALLERID(num)}@default)
exten => _X.,7,DeadAGI(a2billing.php|4)
exten => _X.,8,DeadAGI(a2billing.php|1|voucher)
exten => _X.,9,Hangup