The invention relates to a method for accessing a service from a user's terminal (1) through a heterogeneous network (3) in which several access types (5, 7, 9, 11) are available. The method comprises the following steps: upon reception of a request outputted by the terminal (1) for accessing a service, selecting through an access selection server (17) an access of the heterogeneous network (3) for the terminal (1), said access selection step including a resources reservation step (61) at the selected access; and sending (65) a selected access identifier to the terminal (1) through the access selection server (17).