Systems, methods, and apparatus to monitor mobile Internet activity are disclosed. An example method comprises assigning with a processor a first port number of a proxy server to a mobile device, the first port number to be used by the mobile device when accessing a wireless network via a first wireless access point; associating with the processor, the first port number with an identifier of the mobile device and an identifier of the first wireless access point; generating an instruction document identifying the first port number; and transmitting the instruction document to the mobile device.