I'm gonna answer to myself, cause I have found the solution.
I got an acl on the ip http server, which gave no access to the ip phones.
You have eventually to add in the ios :
url services http://routeraddress-host/ccme.html
or url authentication http://routeraddress-host/ccme.html
The login is provided directly with the service key on the phones.
I didn't test yet without these commands, but for now it works fine :)
Hope this will help some1.
;)