Despite a worldwide recall and numerous efforts to disable Samsung’s Galaxy Note 7, US carrier Verizon said “thousands” of its customers were still using the smartphone.

Verizon told Fortune that it would begin directing all outgoing calls from the Note 7 to a customer service line, except for calls to 911.

“In spite of our best efforts, there are still customers using the recalled phones who have not returned or exchanged their Note 7 to the point of purchase,” a Verizon spokeswoman told Fortune.

“The recalled Note 7s pose a safety risk to our customers and those around them.”

Samsung previously issued a software update to prevent the Note 7 from connecting to mobile networks and disable charging. In the US, Verizon was the only carrier to initially reject distributing the update, but it eventually sent the update to its customers on January 5.

It isn’t clear how customers have still been able to use the Note 7 after the update.

Samsung said in December that 93% of Galaxy Note 7 smartphones in the US had been returned.