34th Signal Battalion (Corps) (Source: Steve Witt) The inside of the AN/MSC-25 Operations Center used as the System Control (SYSCON) element of the 34th Signal Bn (Corps) during an exercise in the field. The MSC-25 was a big tractor trailer shelter. This shelter was the Bn S-3 section's office in the field and was where the status of all the battalion's communications were tracked. This was during the time when the 34th installed a 'command' communications system and all the multichannel radio shots were put in from the Corps Main CP to the major subordinate command CPs. During this time period, a telephone circuit was installed on the SB-22 switchboard in the MSC-25 to a TA-312 field telephone in the multichannel terminal shelter (usually an AN/TRC-117) at the distant end. That allowed the 34th's S-3 to listen to the quality (i.e. noise on the circuit) of each multichannel system and directly talk to the team chief of the TRC-117 (bypassing the chain of command in his company).