At least one of transmissions and receptions over allocated radio resources within a first timing advance group are synchronized using a first timer; and similar for allocated radio resources within a second timing advance group that are synchronized using a second timer. In response to determining that the first timer remains synchronized while the second timer is not synchronized with a radio network which has allocated the respective radio resources, a first procedure is followed for the case in which there is a primary component carrier within the second timing advance group and a different second procedure for the case in which there is no primary component carrier within the second timing advance group. In an exemplary embodiment, a message is sent to the radio network indicating that the second timer has expired. Various distinctions between the two procedures, and how the message is sent, are detailed for different embodiments.