Some, but not all, of the mystery has been cleared up as to why many smartphone users in Hawaii didn’t receive the state’s errant emergency alert Jan. 13 about a ballistic missile on its way to the islands.

It turns out that some mobile phone service carriers might not offer the emergency alert service on every plan, every phone and in every region.

That’s what a federal investigator told state lawmakers Friday.

James Wiley, an attorney adviser in the Public Safety and Homeland Security Bureau of the Federal Communications Commission, is serving as an investigator for the agency examining the state’s missile alert foul-up, and shared the explanation during a briefing for joint House and Senate committees.

Wiley also noted two other reasons that have been previously discussed publicly. One is that phone users can turn off such notifications. The other is that state officials stopped broadcasting the incorrect warning six minutes after sending it out, so any phones that were off or not connected to service during that period would not have received the message.

The fact that not everyone’s mobile service carrier might transmit emergency alerts depending on subscription, phone model or coverage area was surprising to some consumers.

Niu Valley resident Judy Jakobovits said she went to an Apple store after the statewide scare to have a technician tell her why she didn’t get Saturday’s alert on her year-old iPhone 7. “There was nothing wrong with my phone,” she said.

Jakobovits added that her phone was on, was set to accept alerts and had service through AT&T when the Hawaii Emergency Management Agency mistakenly announced the inbound-missile warning at 8:07 a.m.

Jakobovits still doesn’t know why she didn’t get the alert. “At least it spared us from panic,” she said.

A representative from AT&T said she couldn’t comment on Wiley’s statement about emergency alert messaging being limited by carriers.

A Sprint spokesman said the company sends emergency alerts to all customers regardless of subscriber plan and that only old phones that don’t support such alerts would be inhibited from receiving the alert.

Rich Young, a Verizon spokesman, said the company transmitted Saturday’s alert to all its customers in Hawaii without incident. “Verizon experienced no issues with transmitting the alerts in Hawaii,” he said in an email.

Some other companies, such as Hawaiian Telcom, provide mobile phone service through others as a “mobile virtual network operator” that essentially resells another company’s service. Hawaiian Telcom uses Sprint.

State Rep. Nicole Lowen said that the three reasons Wiley described for mobile phone users in Hawaii not getting Saturday’s alert didn’t cover every situation of failed message receipt.

“It seems like there still are some holes in the system,” she said.

Lowen asked Wiley whether the FCC is trying to understand what these holes are. Wiley said yes.