Final answer:
All VoIP services have the potential to be traced, especially those like 911 services that must provide location information. Technologies like microwave and satellite communications have improved the quality and affordability of these services.
Step-by-step explanation:
When considering which VoIP services cannot be traced, it is important to understand that all VoIP services have the potential to be traced to some extent, especially if they interface with the traditional phone network. 911 services, by design, need to be traceable to provide the location information necessary for emergency response. Therefore, the answer is that none of the VoIP services provided as options (911 services, local services, call waiting services, long-distance services) are completely untraceable. The expansion of consumer choice and the development of technologies like microwave transmission and satellite communications have improved the quality and lowered the costs of long-distance calls and have led to innovations such as Internet-based calling.