Amazon’s hardware products that are powered by its virtual assistant Alexa are used for everything from playing music to controlling different aspects of a user’s connected home, telling the weather and more.

Amazon and third-party developers are also adding new “skills” all the time to Alexa’s already impressive library. But what many people may not know is an important limitation of the assistant — something Alexa can’t do, at least not right now, even though a user’s life might depend on it in some circumstances. We’re talking, of course, about being able to call 911.

Many consumers could have easily found themselves in the shoes of someone like Bridget Taylor, a 62-year-old from Jonesboro, Arkansas, who earlier this year took a fall after getting out of her bathtub. Her cellphone wasn’t in reach and she wondered if she could yell out for Alexa to call 911. The Wall Street Journal, which recounted that episode, is out with a piece Wednesday explaining why smart speakers from the likes of Amazon, Google and others — used in some 20 million homes in the US — face a number of regulatory and technical challenges to being able to make emergency calls.

For one thing, the paper notes, internet reliability can be a problem, as is the importance of transmitting precise location data and a callback number for emergency responders.

“Most speakers only offer one-way calling and don’t have the same real-time GPS data that smartphones do,” the WSJ notes. “Even sending 911 caller location data from cellphones has proved challenging because much of the nation’s 911 infrastructure developed around landline phones.

“Creating the ability to call 911 from a smart speaker would require an additional monthly 911 surcharge that customers or the technology companies would have to pay to support emergency call infrastructure. Current monthly 911 surcharges vary by state or county, but typically range from $0.25 to $3.00 and are included in consumers’ wireless and landline phone bills.”

The paper goes on to report that, according to an Amazon spokeswoman, the company’s Echo Connect can make emergency calls since it can be linked to landlines or other home phone services. The standard Echo and Echo Dot, however, cannot.

Dan Henry, director of government affairs at 911 industry group the National Emergency Number Association, told the WSJ he supports adding emergency calling to smart speakers only if the devices are able to provide location information and a callback number.