A method for determining an access right of a user terminal to a first network, wherein the user terminal comprises a subscription of a second network, the method comprising: receiving, in an access server, an access request message originated from the user terminal requesting access to the first network, the access request message comprising a data record for a user name and a data record for a password, determining, by the access server, that the data record for the user name and the data record for the password are in a pre-determined format and that at least one of them comprises data from which a subscriber identity for the second network is derivable, generating, by the access server, an authentication request message from the access server to a server configured to perform authentication related tasks in the second network based on subscriber information in response to a positive outcome of the determination, the authentication request message comprising the subscriber identity derived at least partly from at least one data record in the access request message, wherein the method further comprising: in response to a receipt of the authentication request message generating, by the server, an identification request message to the user terminal causing a request of an access code from the user by the user terminal, in response to a receipt of an access code corresponding to an access code stored in a subscriber module residing in the user terminal generating an identification confirmation message from the user terminal to the server, and receiving in the access server, from the server, information on the outcome of the authentication of the subscriber in the second network, generating, in response to a receipt of a positive outcome of the authentication, an acknowledgement to the user terminal, the acknowledgement indicating right to access to the first network. receiving, in an access server, an access request message originated from the user terminal requesting access to the first network, the access request message comprising a data record for a user name and a data record for a password, determining, by the access server, that the data record for the user name and the data record for the password are in a pre-determined format and that at least one of them comprises data from which a subscriber identity for the second network is derivable, generating, by the access server, an authentication request message from the access server to a server configured to perform authentication related tasks in the second network based on subscriber information in response to a positive outcome of the determination, the authentication request message comprising the subscriber identity derived at least partly from at least one data record in the access request message, wherein the method further comprising: in response to a receipt of the authentication request message generating, by the server, an identification request message to the user terminal causing a request of an access code from the user by the user terminal, in response to a receipt of an access code corresponding to an access code stored in a subscriber module residing in the user terminal generating an identification confirmation message from the user terminal to the server, and receiving in the access server, from the server, information on the outcome of the authentication of the subscriber in the second network, generating, in response to a receipt of a positive outcome of the authentication, an acknowledgement to the user terminal, the acknowledgement indicating right to access to the first network. in response to a receipt of the authentication request message generating, by the server, an identification request message to the user terminal causing a request of an access code from the user by the user terminal, in response to a receipt of an access code corresponding to an access code stored in a subscriber module residing in the user terminal generating an identification confirmation message from the user terminal to the server, and receiving in the access server, from the server, information on the outcome of the authentication of the subscriber in the second network, generating, in response to a receipt of a positive outcome of the authentication, an acknowledgement to the user terminal, the acknowledgement indicating right to access to the first network.