I've received two calls from this number twice today (probably within an hour). No voicemail.

Annoying number that keeps calling when I answer they never say anything and never leave messages when I don't answer.

Just received a call from this number. No message left.

Individual calling from an international call center from ADT.  Continues to call even when asked to cease and desist. States they can continue to call and are exempt from the do not call list.

I keep getting calls from it.

This number keeps coming up on my phone but there is never any message left. It is beginning to get annoying as the calls come 3-4 times a day.

That ADT Security Systems phone number.

Received several calls; never leave message; lists "Unknown Name" - never answered.  They are callling a new phone number which no one has so don't know what it is about.