Many years ago I tried to make a phone ring by pressing a button, for an amateur theater. I tried several old rotary phones and all of them rang with a 12V AC transformer. Could always use a boost converter but need quite a bit of current to drive those old bell coils. When the line is picked up, the 48V idle drops to around 12V.
I was just out of high school, and got them to work with VAC. Just installed a VOIP phone system at work for calls on the air…. A guy from Microsoft said at Redmond and probably their other sites too they completely got rid of normal phones and replaced it all with VOIP and Lync.
Two back-to-back center-tap filament transformers will do it, and isolate quite well. I saw somewhere on the web that someone did this with an arduino and a GSM module to make a old phone cellphone that did drive the ringer bell. Connect the converter's cord to your rotary phone. If your converter does not have an attached section of phone cord, connect one end of phone cord to the rotary phone and the other end to the converter. Connect one end of a phone cord to the converter's output, and then connect the other end of the phone cord to the phone jack or digital device.
Check the manual for any unit-specific instructions. For example, some units require a charging period when first connected before conversion can occur, and some require a powerful connection such as a whole-house VoIP unit to power the rotary phone properly. Pick up the handset and dial the first digit of the number you want to call. That is all I pay.
The Grandstream ATA gives me everything I need to make this system work, including a very strong ring, and rotary dialing. Remember the old Centrex business phone systems? Seeing how I am now able to add my own special features to my phone system, it made me think back from when I was a kid and my school had one of those "Centrex" business phone systems.
These typically used standard Western electric desktop phones and had extensions as well as basic business related calling features. Centrex is a system that operates directly from the phone company. So instead of having a "server" in your building that ties all of your phones together, every phone extension runs directly to the phone central office and all of the calling features are handled on the phone company's end.
So I decided I wanted a Centrex system in my house, and so far it's working out pretty well. My own custom home phone system In my home I started out with a Western Electric push button desktop phone in my living room and a rotary wall phone in the kitchen. I set my living room phone to extension and the kitchen to extension Of course for this to work, each phone is connected to it's own port on the Grandstream ATA.
Each Grandstream HT has two individual phone ports. These ports are in reality their own separate phone lines. Now all of my phones are on one phone number. This means if you call my home, all of the phones will ring at the same time. Of course if I choose I can add code to check incoming caller id and specifically route calls to specific extensions if I choose. When an incoming call is received, that call is connected to that specific extension only. That means if I am using one phone, you can pick up another phone and place an outgoing call simultaneously.
This also means I can do things like transfer a call to another extension, put callers on hold, etc. Eventually I am going to add two more extensions, which means I will need to purchase another HT two more ports.
It works with vintage answering machines! Yes I do have one of these. An old answering machine with the old endless loop tape for the outgoing messages. It's fully functional, but these old answering machines have trouble with voice over IP.
When I used it with Basictalk it had trouble determining when the caller actually hung up. So every message was followed by a fast busy signal that would last for quite a while. The reason these old machines don't work well with voice over ip is because the method of notifying a device the call has hung up has changed. Back in the old days when someone hung up the phone company did what is called a "loop current disconnect", meaning for just under a second the voltage on the line would drop to 0.
The answering machine would detect this voltage drop and interpret it as a hang up. I was very happy to learn that the Grandstream ht has this feature that can be enabled very easily. When I experienced my first hangup I actually felt like a kid when I heard that loud and obnoxious "click" as the line dropped. My vintage answering machine has no issues operating on my line at this point. Like the old Centrex system, but better When I was a kid the only person I knew who had a cool intercom system in his house was my rich friend, back then you had to spend an arm and a leg to get one.
I was always fascinated with how they could make room to room calls and have so many cool features. So naturally as a programmer I have built this type of system in my home. The only thing I did not like about the older systems was the need to dial 9 to get an outside line.
This was because they didn't program the system to intelligently know if you were trying to dial out or trying to dial an extension or feature code. As a programmer this was very simple for me to do. Also I was able to use the same technique to make sure I could enjoy seven digit dialing as well. Basically when a number is dialed, my code analyzes the number and figures out what to do on the fly. So if you were to dial a 7 digit number xxx-xxxx , ten digit xxx-xxx-xxxx or eleven digit 1-xxx-xxx-xxxx , the system automatically figures out that you are dialing an outside number.
If you dial let's say , or , etc, the system knows you are dialing an extension.
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