This Friday marks the 50th anniversary of the first 911 emergency call placed in the United States. Since then, uncounted lives have been saved and people helped. It has been a great accomplishment of government.But even as an estimated 240 million 911 calls continue to be placed annually, the systems that service them have grown obsolete, unable to handle photos, video, downloads, precise geo-locating and even, in most places, simple text messages. Thatís a threat not just to public safety but also to national security.Worryingly, no one seems quite sure how to pay for a modernization to whatís known as Next Generation 911 ("NG911" in industry parlance), whose cost could exceed $20 billion. Why not prioritize an upgrade as part of the Trump administrationís national infrastructure project? Given the dearth of funding in the presidentís proposal, thereís little room for optimism in the short term. And in the White Houseís $1.5 trillion infrastructure plan, a 55-page document released Monday, thereís not a word about upgrading 911 service.Part of the problem is that 911 is a victim of its own success. For much of the serviceís history, people who called the emergency number, which was handled by the single local phone company, could be all but certain the system would work. Calls were answered promptly and handled efficiently, and help would be quickly on the way.Thatís still the case for the vast majority of 911 calls, but glitches have multiplied as technology has aged and Americans have switched to cellphones, from which 80 percent of 911 calls are now made. "Every call to 911 must go through," said Ajit Pai, chairman of the Federal Communications Commission. Yes, but thatís not happening. As the system ages, it will become ever more prone to pranks, hackers and cyberattacks, and ever less reliable. It will also be increasingly vulnerable to collapse in emergencies, unable to reroute calls in the event of natural disasters and terrorist attacks.At the heart of NG911 is a shift to Internet, digital-based routing to replace old-fashioned phone lines. That will take a large helping of funds from Congress, plus significant contributions from state and local governments. So far, thereís little sign of either.