777 is not a valid exchange. Someone is calling you and spoofing the caller ID.
You can probably get the phone company to block that number since they are harassing you. If they start using another number, though, you may end up playing whack a mole with phone numbers.
One thing you MUST understand is that "please take my number off your list" legally means NOTHING to them. They are not required to take your number off their list. What you have to ask them to do is, "
Please add this phone number to your do not call list." They are legally required to keep a list of phone numbers on a do not call list, and they are not allowed to call those numbers once they've been added to that list. Shady companies have ways to get around this, though.
You have two options at this point:
When they call, ignore it. Don't answer. Add the number to your cell phone directory and set the ring tone to none, or block it if your cell phone has that capability.
Alternately, when they call answer no questions. Ask, "Please provide your name and the name, address, and phone number of the telemarketing company you work for, and the company on whose behalf you are calling me." If they refuse, request a supervisor. Do not get angry. Do not swear at them. Don't answer any questions, even if they are yes or now questions. "I refuse to answer any questions until I understand who I am talking to. Please give me your name, and the name, address..."
They generally aren't allowed to hang up except on belligerent callers, so they'll be stuck. Legally they have to provide at least their company's name and phone number.
If you have the capability to record the phone call, learn how to do it, and when they call record the conversation, and inform them that you are recording the conversation.
If they give you the information you are asking for, demand they add your phone number to all of their do not call lists, and inform them that if they call again you will be pressing charges.
Of course there are a wide variety of telemarketer counter scripts for your amusement. An old, but good one, is found here:
http://www.xs4all.nl/~egbg/counterscript.html
And, last of all, if you are really interested in scaring them and/or pursuing them, read up on all the rules they have to follow, and tell them what rules they are breaking when they call you:
http://www.the-dma.org/telemarketing/
All that said, the fact that they are spoofing the exchange number indicates that they are probably not going to follow the rules anyway. At best you might be able to scare them into thinking that you'll actually do something about their calls, and hopefully they will stop calling based on the idea that if too many people get too irritated, they might get caught.
