To send the marks to the parent's cell phone, a GSM modem is required. The modem provides the communication interface. Transports device protocols transparently across the network through a serial interface. The GSM modem is a wireless modem that works with a GSM wireless network. A wireless modem behaves like a dial-up modem. The main difference between them is that a dial-up modem sends and receives data over a landline while a wireless modem sends and receives data over radio waves.