I have recieved two attempts from this number on my cell phone.  I've never been able to answer it since set so it does not ring for unknown numbers.  I keep a very tight control on who has my cell number.  I suspect they are calling all numbers within a certain range. I don't dare call it back for fear it could be identified as a valid number and end up with more calls (similar to what spamers do with email)

This sounds like it may be the same bunch who have called my phone from California.

Got a robo-call on my work cell phone about my car warranty expiring.  When the live human came on and asked for my car information, I asked why he needed it if they already knew my warranty was expiring.  He hung up.

No message left.

called an hang up