Who called from 2315775010

Several calls appeared on caller id.  Never a message.

Repeated calls I didn't answer. Finally did answer today and a woman asked for Christopher. No one by that name lives here. When I asked who was calling she said "are you his wife". Then I asked what number she called. She replied "I'll just call back later" then promptly hung up the phone.

Caller keeps calling though I have asked them not to call back.

Called today for first time.  I usually don't answer caller unknown but am sick of telemarketers.  When I answered he said welcome back and laughed a scary laugh and hung up.