NEW YORK: They're not ignoring you, it's just WhatsApp.

The popular messaging service owned by Facebook was intermittently unavailable for several hours Thursday, delaying New Year's Eve messages for some users.

Facebook Inc. says WhatsApp has about 900 million global users.

WhatsApp says it is working to fully restore service. The company did not answer questions about the cause of the outage or when it started.

Facebook also had a glitch on its flagship service Thursday that invited some users to celebrate "46 years of friendship on Facebook" with one or more of their online friends.