Call it the “silent prank caller.”

For months, Jennifer got inexplicable calls to her cellphone, all from the same number. She rarely answered, but when she did, the line was silent.

Googling the number, she found it listed in WhoCalled.Us. It’s like a social reverse phone directory. People post phone numbers, often telemarketer’s, and others add comments. They share advice about the caller’s identity and in some cases, how to get them to stop.

Perusing the listings for the number calling her, Jennifer found it was Sprint! When she called Sprint customer service (god knows how she got through), she learned that the number an internal company machine calling customers to tell them about special offers, though it seemed to have laryngitis as of late.

Sprint doesn’t let cellphone customers block incoming calls. However, the customer service rep did take Jennifer’s name off the list Sprint calls with promotional offers, ending the annoying stream of calls.

Add another one to the list of crappy automatic systems has that can potentially invade your privacy.

“WhoCalled to My Cell Phone Rescue” [Gearlog]

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.