This morning the pbx took a call and played his messages correctly when i see the call monitor. But the caller (gsm) was still waiting that the call was picked up by the pbx. So the GSM was waiting to make a connection and the pbx had already taken the call. On the GSM bill the connection was never made. This took place this morning between 0:10 and 0:30 with several phones. Knows anybody what it could be ?