It’s hard to underestimate just how much work is ahead in the quest to establish what happened to Madeleine McCann – but this a very significant moment for the investigation.
This is the first time in the six years since she vanished that there has been a comprehensive attempt to establish just who was in the area at the time.
It doesn't matter whether a phone call was made, simply that the phone was there is enough to trace it. Police won’t say how many phones they are tracing but they are owned by people from 31 different countries.
They have asked police forces in all of those places to check out who is associated with which number.
It means locals and holidaymakers may get a call in the coming months and be asked what they were doing in the area, why they were there and if there is any information they may be able to add to the inquiry.
Of course the great focus will be on phones close to the apartment at the time when Madeleine went missing. The hope would be that one number would connect to someone of interest to them and the network of calls made by it may help unravel the mystery.
The fact that police also believe they will be able to offer significant new information in the Crimewatch programme coming up later this month is also likely to be encouraging to the McCann family – every new bit of information tends to generate new information from the public. Even now there are calls every week.
That similar programmes will be broadcast in the Netherlands and Germany, where many holidaymakers were from, also raises the prospect of increasing Madeleine’s profile in countries where it hasn't previously been high.
No-one on the investigation will say how just how hopeful they are, simply saying their wish is that fresh eyes looking at all the information in one may well lead them to some or all of the answers they seek.
Emma Murphy reports on how new developments in mobile technology are being used in the search for Madeleine: