DCU means the C-track Driver Communication Unit, also named a driver communication console. With this equipment the fleet manager and drivers are able to perform two way SMS and voice communication. SMS messages and dial numbers are pre-defined with the C-track base station software. For voice communication, a voice kit is required and can also installed without the DCU.
You can set the maximum talk time duration, using the same software, in order to reduce communication costs.
Using the DCU with voice contributes to driver safety because drivers does not have to dial and to hold the communication equipment in their hand.
Many companies require the DCU with voice equipment to standardize communication instead of using private mobile phones.