Just about everyone knows that in an emergency, the first thing to do is to call 911. However, as comedian John Oliver pointed out Sunday, the 911 emergency response system in many places across the country cannot be fully trusted.

Oliver spent Sunday's episode of HBO's "Last Week Tonight" highlighting various systemic problems with the 911 emergency response system across the U.S. He noted that in many places, the system's technology has not been properly updated with the ability to accurately locate cell phone callers and that, in many states, the emergency dispatch system is dangerously understaffed. 

"We have a lot of faith in 911," said Oliver. "But the system can break down more than you think; and when it does, people can die as a result."

Oliver pointed out that one big problem is that, in many places, the 911 system does not yet have the capability to identify callers' locations from their cell phones, unlike tech services such as Uber and Lyft, or even Domino's pizza delivery. The comedian noted that the FCC has mandated 911 dispatchers be able to locate cell phone callers accurately 80 percent of the time by 2021, but Oliver says that is far from good enough. 

"Ubers can find you better than ambulances can," joked Oliver. "Depending on where you live, [911 dispatchers] may also be underfunded, understaffed and full of outdated technology — which is fine, if you're describing a Radio Shack."

In addition to funding shortages and understaffed call centers, Oliver put some blame on the callers themselves. Across the country, Oliver argued, the system is overwhelmed with trivial calls, duplicate calls (as a result of the ubiquity of cell phones) and a shocking amount of "butt dials." 

"We have an antiquated, disjointed system populated by workers who are understandably sick of listening to people's butts," said Oliver. 

Oliver ended the segment with a parody PSA featuring comedians Rob Riggle and Wendi McLendon-Covey playing a firefighter and 911 dispatcher explaining to a group of kids why the emergency response system is failing them.