I was helping someone with limited mobility who wanted to have independent use of her phone with a single adaptive switch. Her preference was to use operator assistance to place their calls. This phone hardware modification is a One Button Operator Dialer. With a single adaptive switch press, the line will open, ‘0’ for operator will be dialed, the Verizon menu will be navigated, and you’ll get to speak to an operator who can help you place a call. A second press ends the call. If you just want to open the line (without the operator sequence) you do a quick press (less than 1 second). Here’s a video of the first prototype in action:
Here’s the inside of the phone when I first opened it:
You can click on these pictures to see closeups of the hook switch. It functions as a combination of 3 switches: 2 SPST’s and 1 SPDT
First I worked out which points on the keypad circuit I could use to dial ‘0’. Then I traced the wires from the hook switch to see which connections to make for the 2 states. With that information I used 3 relays for the 3 hook switches and a 4th relay for the ‘0’ key. It took some trial and error to get the timing right for the operator sequence. With Verizon service in this area, after dialing ‘0’ there’s a delay, ringing, then a menu begins, during which you can dial ‘0’ again to get a live operator. However that ‘0’ I had to discover as it’s not mentioned in the menu, also you can’t hit it right away or else it’s ignored. It must be dialed after the greeting mentions pressing ‘9’ for fire or police.
Here are some pictures of assembling the first prototype using mechanical relays. I went with mechanical relays initially since they are what I had on hand but they were not necessary nor ideal for this project (large, loud, power hungry), but they worked.
Here are some pictures of assembling the final version using solid state relays. In this setup everything fits inside the phone and only a switch jack and indicator light are external.
The user of this device wanted to be able to use her check activate the phone switch but the positioning was crucial. Otherwise the user would either not be able to hit the switch or would hit it by accident. To get the right spot I cut a notch in the center of the handset and placed a microswitch in there.
The logic to detect the length of switch press and operate the hook switch and/or get to an operator is running on an Arduino Nano. You can get the code here: