1. A method, comprising: receiving, at a first network device executing a device simulation tool, a selection of a second network device in a communications network; receiving, at the first network device, a selection of at least one use case, scenario or error condition associated with operation of the second network device or the communications network; executing a network simulation of the communications network based on the at least one use case, scenario or error condition; generating a call flow diagram, that involves the selected second network device, based on the executed network simulation; and providing a graphical display of the generated call flow diagram.