Call Log not showing all calls

[Novais]

All calls to this phone will be coming in from the Ring Group but not all calls from the Ring Group are being registered in the Call History. All calls are showing up with the caller ID while the phone is ringing but then will not show in the history. Unfortunately it doesnt appear to be a regular error so it may be a large capture and we would have to run it until there was a call that didnt register. Would you still like me to run the capture?

Thanks.