[Freeswitch-users] NULL ESL events on hangups to certain numbers

I use the ESL to listen to Freeswitch 1.2 for call events. The events I'm listening to are CHANNEL_HANGUP and CUSTOM. For certain phone numbers, I will consistently get NULL events when calling them and the call dies. Again when this happens, its only with specific phone numbers, but all the time with these numbers. (NULL, meaning when I var_dump the freeswitch ESL event, the event is simply NULL, not a populated event object.) Any ideas?