Until very recently truck drivers were limited to their cellphones when they needed to call dispatch or home.

Today Vocalis allows dispatchers to see the location and talk with the drivers one-to-one or grouped anywhere on the continent with a simple press of a PTT button.
Every commercial driver has a cellphone in their pocket (Android or Apple). Most are on AT&T or T-Mobile and both have areas without service if you are using only one network.

The solution?
Unlock your phone and switch to Datalink's SIMs with auto-switching between AT&T plus T-Mobile and get much better coverage.
Better still, install a VOC100 mobile in the cab with a network agnostic SIM and talk to the office or other drivers on your team. Be part of a conference call from the cab. Datalink’s SIMs and open cellular service covers USA, Canada, and Mexico. Automatically switching when you cross the border.