1. An apparatus comprising: a processor; and a memory, the memory storing instructions that, when executed by the processor, cause the processor to: access a pre-designed graphical user interface (GUI) framework; load into the GUI, simulation of first and second endpoints, wherein the first and second endpoints are configured for voice-over-IP communication; load into the GUI, representations of telephony objects; load into the GUI, an interactive user control panel; display the GUI on a computing appliance monitor; receive, via the GUI, user actuation of a first command to initiate a simulation of a voice-over-IP call from the first endpoint to the second endpoint; transmit, in response to the first command, an invitation by the first endpoint to the second endpoint; display, via the GUI, in response to the transmitting, a state of the invitation with respect to both the first endpoint and the second endpoint; receive, via the GUI, user actuation of a second command to accept the voice-over-IP call from the first endpoint; simulate, via the GUI used to initiate the simulation of a voice-over-IP call from the first endpoint to the second endpoint, in response to receipt of the second command, acceptance of the voice-over-IP call by the second endpoint; display, via the GUI, in response to the simulated acceptance, a state of the voice-over-IP call with respect to both the first endpoint and the second endpoint.