The far CALL instruction is used to invoke a subroutine. The instruction first pushes CS into the stack, and then pushes IP. Next, it updates CS & IP so that they contain the selector:offset of the first instruction in the subroutine.
The far form of the RETurn instruction first pops IP, which restores the saved content of IP, and then pops CS, restoring it as well. Execution continues at the instruction following the CALL.