Spam Eliminator Telephone System

From the department of Counter-Intuitive Thinking: Keep your land line!

In playing with technology, I inadvertently found a system to eliminate spam phone calls.

How Spam Phone Calls are eliminated

Modern PBX systems force the user to create a menu which is delivered to help the PBX route a phone call. This is the voice that says “Press 1 to reach X”. Well it turns out that 99% of spam callers have an automatic hang up when presented with a menu. The 1% remaining spammers are usually live people calling to scam you. For one of the two systems I created, for my 90 year old mother, I only have known numbers ring her actual phone, all others get a please leave a voicemail message. Since voicemail on the freeware PBX (call Asterisk) can transmit the voicemail to your email inbox, you can listen to the remaining humans and their voicemail.

So the concept is that you would keep your landline and use it any time you need to give out a phone number. You provide your cell number to anyone who you are OK with contacting you at any time.

Knowledge you need to do this:

Before I explain in detail how to do it, creating this system requires some ‘jack-of-all-trades’ experience in a number of areas:

Unix user experience
Some Unix system experience
some exposure to a PBX or the willingness to play with a PBX system
Some IP networking experience, including configuring static IP addresses and configuring weird devices like IP Phones.

System Overview

I have created two systems, one for my house, and one for my elderly mother’s house, that have tow different functions, but both eliminate all spam.

The basic overview is rip out all existing phones and answering machines, install a device which converts calls in and out to VOIP (Voice over TCP/IP), use a raspberry pi unix box as the brains of the system, and place a set of VOIP phones around the house depending on the needs.

The Equipment:

1 Obihai OB110 VOIP Telephone Adapter: $60 Amazon
1 Raspberry Pi with case: $39.99 Amazon
2 8GB SD card (use one approved for Raspberry PI) one for backup
ethernet cable for the Raspberry PI
VOIP Phones depending on application

The Software:

Asterisk for the Raspberry PI: Free (also known as FreePBX)

System 1: The Landline is Our Office Phone

In this configuration, each member of the family has a VOIP desk phone that is their home base for voicemail. You create an voicemail box for each member, and configure each VOIP phone as an extension using Freepbx. You link each Voicemail box to an email address. I used a cisco SPA 303 – 3 line phone for each desk ($94.22 each).

System 2: Only Known People get to make my phone ring

With a VOIP phone that looks like an AT&T Trimline phone next to my mother’s bed and a VOIP adapter connected to her answering machine, I created an electronic phone book of approved numbers which will call the phone in her ring group, everyone else goes to a spam menu (“press 1 to leave voicemail”). I used a cisco 3102 adapter to connect the answering machine and cisco 301-g VOIP telephone next to the bed.

What I learned

Both systems eliminate 5-15 calls a day from spam sources.

Here is a detailed followup for this blog entry.