I love to see the interest in this subject. Personally, I think we need telemarketers a little less than fleas, mosquitoes, and politicians.
It is my ambition to put together a system that can be given away as a promotional device like ball point pens or refrigerator magnets. so far, I have a system that works but, it would make a very expensive refrigerator magnet at hobbyist prices.
It is completely stand-alone, it uses the Mega2560, the HT9032 receiver, the Seeed 240X320 TFT display/SD, the Osepp RTC/SD, and the Emic2 text to speech talker. I have incorporated a couple features that have not been mentioned so far.
1.) Since I have two SD cards, I use one to hold the message played for the blocked caller. I do not simply block the call and let it go at that. To reduce the likelihood of a repeat call I play the triple tone followed by 'The number you have reached has been disconnected or is no longer in service.' I use the the Simple Audio which requires audio stored on a clean SD.
2.) Since the telephone companies are encouraging telemarketers to spoof their CIDs, I have gotten calls from numbers from power company, doctors offices, IRS, insurance company, I have even received calls from myself. The problem with simply blocking these calls is that I may be blocking legitimate calls. My reasoning says that a telemarketer won't stick with a particular spoof number for an extended amount of time. By simply scanning the time stamp on the call records I can purge the blocked calls after a settable amount of time.
I can do searches, printouts create/edit white lists, and other features that have been mentioned here. My system works quite well but I am not good at packaging so it is not impressive to look at. Also, I have been an amateur programmer since 1975. My code is not pretty either. I have been thinking about incorporating the components unto a single circuit board to avoid the high hobbyist prices but not until I reach a plateau in the development.
Did I mention that I am not fond of telemarketers? For several years I have been asking who is behind the push to eliminate credit card interest and why it is so important to them that they must ring my bell 5 or 10 times a day. I have tried many times to see where they are going with their presentation. So far the only conclusion is that they simply do not want me to answer my phone. Why??? Who??? Why cant calls be traceable, like emails? Did I say I don't like telemarketers?