serveur billing et asterisk

Bonjour, je viens d'installer mon serveur de facturation pour le faire communiquer avec asterisk, seulement je ne peux pas être d'appels. Voici mes erreurs
Using SIP RTP CoS mark 5
-- Executing [00221771055507@billing:1] AGI("SIP/1002-00000017", "agi_script.php,'Connect'") in new stack
-- Launched AGI Script /var/lib/asterisk/agi-bin/agi_script.php
-- <SIP/1002-00000017>AGI Script agi_script.php completed, returning 4
== Spawn extension (billing, 00221771055507, 1) exited non-zero on 'SIP/1002-00000017'
-- Executing [h@billing:1] AGI("SIP/1002-00000017", "agi_script.php,'Disconnect',,,") in new stack
-- Launched AGI Script /var/lib/asterisk/agi-bin/agi_script.php
-- <SIP/1002-00000017>AGI Script agi_script.php completed, returning 0
== Using SIP RTP CoS mark 5
-- Executing [1001@billing:1] AGI("SIP/1002-00000018", "agi_script.php,'Connect'") in new stack
-- Launched AGI Script /var/lib/asterisk/agi-bin/agi_script.php
-- <SIP/1002-00000018>AGI Script agi_script.php completed, returning 4
== Spawn extension (billing, 1001, 1) exited non-zero on 'SIP/1002-00000018'
-- Executing [h@billing:1] AGI("SIP/1002-00000018", "agi_script.php,'Disconnect',,,") in new stack
-- Launched AGI Script /var/lib/asterisk/agi-bin/agi_script.php
-- <SIP/1002-00000018>AGI Script agi_script.php completed, returning 0

J'ai l'impression que mon asterisk ne peux pas lancer le script.
Merci de votre aide.