Transmitting IP-based telephone calls (VoIP) over a Wi-Fi network. Voice over Wi-Fi (Vo-Fi) provides enhancements to the 802.11 standards for handling the real-time environment of voice calls. With a single mode Vo-Fi phone, users can make calls only within a Wi-Fi hotspot. With dual mode phones that switch between the cellular carrier and a Wi-Fi hotspot, calls can be made by the most expedient method. In addition, calls will not be dropped when walking from the outside into a large office building.