I get this call too. I have found that it is some sort of collection agency for Sprint. As I have never had an account with Sprint or any of it's affiliates, I will be answering now to let them know as such. They never leave a message and call at the oddest of times. I do not know the name of the collection agency yet. But I will find out.
724-602-2015 Not to worry. Log every call. Let them hang themselves, log 15-20 calls. Date & times.
Call the 724 area code carrier, i.e Verizon, At & T. Notify the Attorney General in that state as well as your own state. Call the Police Dept in their jurisdiction and lodge a complaint. Now, once you find out who they are, ask for the principlal of the company along with their personal addresses. Next SUE! What they are doing is illegal & they know it. Remember log all the calls.
These calls from this number just started to come in the past two days. 4 calls so far. No messages. I dialed the number to see who/what would answer and heard background noise then nothing...