I've received 2 calls too and I actually answered one this morning. The caller identified herself as "Helen" then there was static and the call was lost. Pebble sounds likely since I received a packet from them a few days ago addressed to me personally. I don't know how they got my name and address.
Repeated calls from this number. no area code shows up (which must mean it's 907, the alaska area code), and no name -- although it doesn't say private name or unknown. makes me suspicious that they'e blocked it.
PLP - Pebble Limited partnership lists this number in their online information. I've gotten 2 calls (I didn't answer) in the last 2 days and a packet of propaganda from them earlier this month.