Problem . GSM
GSM has logical control and traffic channels. "Common Control Channels" (CCCH) are used for signaling between a Base Station (BTS) and a mobile station (MS). "Broadcast Control Channel" (BCCH) is used to broadcast, for instance, information about the cell configuration and identity. Use wireshark on the following PcapNG capture to answer the questions:
(a) Find "CCCH System Information" BCCH messages. What is the MCC, MNC, and LAC of the BSC? What carrier frequencies does the BTS support (hint: find the ARFCNs). Explain where you found this information.
(b) Within the CCCH are "paging request" messages. Explain the purpose of these messages, and provide a TMSI observed in a paging request.
(c) Examine the raw hex bytes of the GSM messages, especially the end of the messages. What is the most frequently observed byte, and what is its significance? Explain your answer.