Parallel traffic(voice and data?)

A would ask somebody, whether iPhone is able provide parallel data transfer/communication. In example:

I use waze application(navigation system). When I receive call, it seem that waze stop communicate and I did not receive new information and waze do not recalculate the best way. I use iPhone 5S. When I stop voice call, waze show error message"any data connection", it take couple of second(20-120), after reconecction waze continue in normal state... Is it feature of waze? Or feature of iPhone. Or if I do voice call, is it impossible that waze communicate with server in parallel? During voice call is waze running, but it seems like sleeping mode without communication with server.

Thank you for help, explanation in advance!

Juraj