I receive about 2-3 calls per day on my fax only line.  This has  been happening continuously for 3 months.

yea its been 2-3 months for us also. It started off as a woman asking for both my parents by name then just my mom. Later after a couple weeks it turned to a guy, when I ask what it was regarding he said he would call back and hung up. Ever since then he calls numerous times a day either 3-5 times dailey, no answer and just pure silence in the background. It gets very annoying esp since couple of those calls would be during my 6 month olds nap and it will wake her up.

yep, back to back call/hang up purportedly from 213-915-3175.  No message  They called at 9:35am Pacific

Random call.  No message left.

This number has been calling a couple times a day for the last month or so and they never leave a mssg. The caller ID say Los Angeles CA and then the number. I don't answer or return calls that do not leave mssgs, so this is all the info I have.