Asterisk not handling multiple call files

We are trying to send about 100 call files into the outgoing folder for * to pick up for automated outbound dialling. Each file is placed in there at 200milliseconds apart but * does not process all of them. Out of 100 placed in there about 30 got processed.

This is what’s placed in the log:

pbx_spool.c: Call failed to go through, reason 0

Does anyone know why * has a problem with processing multiple call files at once?

Thanks.

What sort of Trunk are you using? Are you moving the files or copying them to the outgoing spool directory?