A positioning system (e.g., GPS) integrated in, or coupled to, a mobile device determines the position of the mobile device. An availability status manager (ASM) in a vPBX acquires the position of the mobile device. The ASM can contain rules on how to route or otherwise control incoming phone calls based on availability status of one or more mobile devices in the vPBX network. When a call is received by the vPBX, the ASM determines the availability status of the receiving mobile device based on the geographic location of the receiving mobile device. The ASM then routes the call to the receiving mobile device, to another mobile device, or to a landline based on the availability status of the receiving mobile device and the availability status based rules.