In given user equipment seeking access to a first communication network (e.g., 5G network), wherein the given user equipment comprises a subscriber identity module (e.g., USIM) configured for a second communication network, and wherein the second communication network is a legacy network with respect to the first communication network (e.g., legacy 4G network), a method includes: initiating an authentication procedure with at least one network entity of the first communication network and selecting an authentication method to be used during the authentication procedure; and participating in the authentication procedure with the at least one network entity using the selected authentication method and, upon successful authentication, the given user equipment obtaining a set of keys to enable the given user equipment to access the first communication network.