Phone ringing early morning, no phone number shown.

Was woken early morning, about 3am, when landline phone rang, had 2 more calls shortly after. Turned over, were very long rings, nearly got up to answer!  Checked for number when I got up and no number shown.  Could this be an international call?  No message showing private number or international number shown.  Annoying to be woken early morning, would block caller if I knew the number!

My landline rang a couple days ago around 2 AM.   It rang only twice.  There was no caller ID information.