System command causing frustration

When executing the system command in a context, Asterisk is executing the command but it seems the command is properly running.

The context looks something like:

exten => 1111,1,system(/usr/bin/php /etc/asterisk/custom/script.php ${CALLERIDNUM} &)

The ‘test-context-custom’ context is included into the [from-internal] context (this is TrixBox). When watching the CLI with verbosity set higher, I can see that Asterisk is indeed executing the command. However, the command isn’t actually doing anything. When I copy and paste the exact command you see above to the command-line, it works perfectly. Is there anything after the system command I should put? The call is continuing on as normal, so I assume control is being returned. The ampersand is in there so the script runs in the background and does not hold up the dial plan. Any ideas?