Caller ID said "Customer Srv". I did not pick up. They didn't leave a message. Surely a telemarketer or robo-call

I called back.  If you would like to be put on the do not call list for the number that called you, please press 1,
Well if I knew who was calling me, that would help!

Don't ever push one.  I am getting a lot of these calls lately.  I read on another site that when you press 1, (thinking you are being added to their do not call list, they are actually accessing your computer and your personal information.  Not sure if that's what is really happening but why take the chance?

they called and left no message tired of this BS ........

Called my cellphone. They left a voicemail, a recorded message that only began halfway through the message. I don't know what they were selling but the message said "you must be a homeowner" to take advantage of this offer. Then I heard the "press 1" or "press 2" to be removed from their calling list. Of course, it was a voicemail so pressing 1 or 2 would not do anything for any call list.