That's funny - INMARSAT is an old system the Navy used to have (and may still have) on its ships. It's used to make satellite phone calls while a ship is out at sea. It was mainly used by sailors to make family emergency calls, since it cost @$10 a minute to use.
For a month or two calls from this 11 digit number to my cell phone are relentless. I blocked it w/ Verizon yesterday but you all are right. I guess non-US or 11 digit numbers can't be blocked. I went online and downloaded a silent ring tone and added the caller to my contact list, assigning them that ring tone. Now at least they won't ring my phone. For the IPhone, I used http://richardkmiller.com/702/iphone-tip-use- ... s-in-your-sleep. It's free and seems to work. Another paying option for IPhone is the Silent Sound app. It takes several steps to download but you can also create other ringtones from your iTunes music list.
I got a phone call from this number at the same time everyday. It just started a week ago, until I let my husband answer the phone and some guy answered asking for some one we didn't know and then it stopped. Every time I answered they said nothing.