To improve network coverage or reduce false handover triggering, at least one client terminal is set to operate as a virtual access point (VAP) in a first wireless network by an AP controller. If a mobile device detects that a signal quality estimate of communications via an AP of the first wireless network is below a first value, the mobile device performs a handover procedure to the VAP. While maintaining the call via the VAP, if the mobile device detects that the signal quality estimate is back above the first value, the mobile device performs a handover procedure back to the AP of the first wireless network. On the other hand, if the mobile device detects that the signal quality estimate is below a second value which is less than the first value, the mobile device performs a vertical handover procedure from the VAP to a base station of a second wireless network.