All my 4 iphones at my company stopped conneting to our Exchange!

Hi,

This sunday, all 4 iphones stopped being able to connect to our internal Exchange 2007.

All my employes with Android still works perfectly.

The iphones are crazy cheap for providing a start of troubleshooting idea... this thing just says "Impossible de relever le courrier La connexion au serveur a échoué" which roughtly translate to "impossible to pickup the mails. The connexion to the server failed".

Off course it doesn't tell any details that could have help... rrrrrrr

It cannot be a bad configuration in the mail settings of the iphones since:

1- 4 Iphones stopped working at the same time

2- None of my users went sunday in his configurations and changed something.

What could it be?

Why would the iphone don't say something usefull like "I don't like the certificate" or "I don't like the TLS version you are using" or something!

Where can I start?

tx