To establish a communication channel for the telex service in the INMARSAT-A terminal, you should first（）.

A. establish a communication channel from the CES, via the International Telex network to the final destination
B. set up a communication channel from your SES, via a satellite, to a CES within your ocean region
C. set up a channel directly to the addressee at the destination
D. establish a channel from your terminal, via the International telex network to a CES within your ocean regio