Your weekend modder project: getting your rotary phone to work with Vonage

Why am I devoting service space to this product? Read on...

On the independently-owned and run Vonage Forum, I've run across a fascinating thread in which a user named Cozzman is trying to figure out if there's a way to use his Vonage service with his rotary phone.

My first thought: I flashed back to the rotary dial phones of my childhood (longer ago than I care to state here), and then wondered why someone would want to use a futuristic technology such as VoIP with hardware you are more likely to find packed away in attics or offered on eBay than in day-to-day use.

Then, after reading Cozzman's post, I got it. Just like some people still build radio-controlled antique cars, the challenge of marrying old and new technologies is the kick here.

In the Vonage Forum thread called Antique Phones and VOIP (Pulse to tone), Cozzman writes:

There are products out there that convert pulse to DTMF (touch tone) but they are all astronomically high for the parts contained in them. They run $49 plus shipping (or there abouts) to get an old/antique pulse (rotary dial) phone to be able to dial out with Vonage. I don't suppose this will be a popular post because how many tech-ies that can handle VOIP concepts also appreciate the finer points of "ancient" telephony but I'm emploring anyone that has a good feel for tone generation and some curcuit board knowledge to come up with a cheap alternative.

I have found very rudimentary circuit board diagrams to do what I need but for a different application that I don't have the background enough to adopt to my scenario but seem extremely simple as circuit boards go. Far simpler than the AM/FM radio I made in my childhood. I can't be the only one interested. These things should run about $3 in materials and I'm willing to pay $20 for them. I'm sure I sound cheap but paying $50+ to get some old phones working on a system that is suppost to be saving me money over the big company alternative just seems against principle. If I wanted to spend money to get things working the way I want them I would have stuck with Verizon to begin with. 

Guess what. Cozzman got several helpful replies, including some from the very VoIP "techies" Cottman feared would turn up their collective noses at the very idea of the type of project he's proposing.

"A post from voip-info might be of interest to you," writes a Vonage Forum Member named scerruti. "It suggests attempting to use a Mitel Smart-1 dialer (approx $18 ) to do the pulse to DTMF conversion. I think the price in that post was off though.
"Another option," scerruti adds, "would be to use a pocket tone dialer. These used to be quite common for controlling answering machines from rotary phones.

Scerruti points out that he is not personally recommending the TD-122 KXT-41 Tone Dialer (shown at the top of this post) but is posting it as an inexpensive example.
One other option cited by scerruti is a separate keypad that is connected to the phone wiring like the Touch Tone Dialer Kit (shown below but currently sold out).

"While again not the ideal solution, it is a workable one," he adds.
"Are you trying to preserve rotary dialing, or just keep the older phones?," scerruti points out. "There are other external keypads like the one above that might give you added functions like speed dial, emergency numbers and caller ID."

Hmm..sounds like an interesting tinkering project for a rainy weekend coming up...