Do not move calls to Voice mail. If you get lots of telemarketing calls, it can add up fast and then you will have to waste much time deleting those from your VM box.
I have been using the no ring tone, "ignore" option for all numbers from repeated calls I see on my recent caller list. This doesn't work for absent number, however. In my contacts, I have T1, T2, T3, contact names, each contact has many allowed numbers that are treated the same, like home, business, fax, etc. I just assign any of the nuisance calls to one of those options until the contact is full, then move to the next. That helps keep the number of contacts and file size small.
Recently, I have seen a large number of new telemarketing calls go to VM and some leave a message, to call back and some just say nothing but register as a VM. I reduced this nuisance somewhat with a rather rude message that starts with,
Hello, If you are a telemarketer, do not ever call this number again, remove me from your list, now hang up. If you are still listening, I will never call you back. If you think this doesn't apply to you, go ahead, make my day, and see if you live to regret ever bothering me with your nuisance call. All others, if I know you, you know the drill.
This has actually cut my VM telemarketing messages to only 1 last week. Since I am no longer in business and retired, I think that gives me the right to be a cranky old curmudgeon. Callers beware!
I tried another one just for fun but it didn't stop a few morons from punching in a random set of numbers. It went like this.
Hello, If you are a telemarketer, authorized to speak to me, please enter your 7 digit pin now. It amazed me how many of these morons actually entered seven numbers and then thought I was now on the other end ready to talk to them.
My daughter used to work for a company as a telemarketer when she was in college and she tells me my VM's are actually entertaining and break the monotony of the job.