@jmmilner: thank you for answer.
What you are seeing is due to the cell or cells in range being fully subscribed.
You could be right: I have not enough "data" to exclude this... but I am not conviced
Hope I can try again soon!
May be someone ask this question in the next conference: are all the known phone numbers of the pax been searched for connexion or a simple "ping" on the 03/08 after 01:20?