CICS is a TP-monitor that is able to communicate with a lot of different systems especially other CICS systems. If you have acces to the CEMT transaction you are able to find out which systems your CICS can communicate with. Typically some or most of these systems are other CICS systems and those systems you can switch to from your CICS.

From the blank CICS screen you type in the command CEMT I CONN (CEMT I C is enough) and hit Enter. The result is a list of all connections to other systems from your CICS. The name of the connection is in Con(<name>) and the VTAM name is in Net(<VTAM-name>). After these two parameters there are some parameters describing the state of the connection. It is not possible to tell which connections are related to other CICS systems, so here you need to have some knowledge about the site.

With the appropriate knowledge it is possible to switch to another CICS with the CRTE transaction. On the blank CICS screen you execute a CRTE SYSID=<name> where <name> is the name of the connection. After a succesfull execution of the CRTE transaction all subsequent transactions are routed to and executed by the CICS system you switched to. Maybe you need to logon to this CICS system. For this purpose you normally use the CESN transaction. When you are tired of using this other CICS you return to the CICS where you issued the CRTE transaction by executing CANCEL on the blank CICS screen. The "normal" CESF LOGOFF refuses to work and CANC is not enough because CANCEL is not a transaction, but a command to CRTE which is in control.

Speaking of the CESF transaction you should try entering CESF LOGON instead. This is the same as entering CESF LOGOFF because CESF only checks the first 4 characters of the word entered after CESF and a blank. CESF also accepts GOODBYE and GOODMORNING giving the same result as LOGOFF no matter how strange it might seem.