The present invention relates to an arrangement and a method respectively for providing an end user with access to an IP network (login). It comprises a user station, an access server of an access network, a web server and an authentication server. The end user station comprises first means for communication with the access server and second means for communication over a mobile telecommunication system with the authentication server. The access/login procedure comprises a first and a second phase, the authentication server controls the first phase comprising a one-time-password (OTP) login sequence, and, if the one time password (OTP) is valid, the second login phase is performed in order to login the end user at the access server, by creating a temporary account for which user credentials are defined.