I haven't seen any 11 digit numbers personally... O.o
My best semi-educated guess is that the caller is spoofing their caller id (quite common and simple, and bills have been intriduced in Congress to make it illegal) to show a fake number that has more digits than normal.
In the last month or so, I have noticed that I am getting repeat callers with phone numbers with 11 digits. From reading other similar discussions, I am glad to hear that the unwanted caller is made aware of their status when calling your phone. However, I have noticed that the call block feature will not allow me to block these particular calls with 11 digits, not ten. I am unclear of the source of these calls, and am worried that they may be international callers that have somehow procured my number. The one timeI actually answered such a call (4 calls from the same number in 2 hours), the caller actually told me that she did not speak English! I was infuriated! I did not call her, she called me! I am very worried that such calls could be some type of scam call in which the caller will charge future calls to my account or some other horrendous effect. At the least, they are annoying and disruptive to my day and night (the calls come as late as 10 P.M.).
So my questions are these: How do I block these types of calls from 11 digit numbers? What is the source of an 11 digit number? How do I find out where these calls are coming from - caller ID only shows the number, and call lookup cannot identify the numbers as they are seemingly not based in the US, unless there has been a change to the standard US phone number format.