A Blast from the Past: Connecting Your Bakelite Phone to a Modern VoIP Line

There’s something undeniably cool about an old Bakelite telephone. The satisfying, mechanical thunk of the handset returning to its cradle, the rhythmic clickety-clack of the rotary dial, and the solid, weighty feel of the device in your hand. These aren't just phones; they're pieces of history. But what happens when you try to connect one to your modern Voice over Internet Protocol (VoIP) line? The charming nostalgia can quickly turn into frustrating silence. The good news is, you can often bridge the gap between these two technologies and get your vintage phone working again. 

The Problem: A Tale of Two Technologies

The fundamental issue lies in how these two systems "talk" to each other. Old rotary dial phones use a method called pulse dialing (also known as loop disconnect signaling). When you dial a number, the rotary mechanism interrupts the electrical current in the phone line a specific number of times. For example, dialing a "4" sends four quick electrical pulses to the exchange. The exchange then interprets these pulses to connect your call. It's a simple, brilliant, and entirely mechanical system. 

However most modern VoIP systems don't understand pulse dialing. They rely on a completely different language called Dual-Tone Multi-Frequency (DTMF), or what we commonly know as "touch-tone" dialing. When you press a key on a modern keypad, it generates two distinct tones—one from a low-frequency group and one from a high-frequency group. The combination of these two tones is unique to each number, and the VoIP adapter recognizes this pattern to route the call. Think of it this way: a rotary phone is speaking in Morse code, while a VoIP line is listening for musical notes. They simply can't communicate directly. 

This is why you can often receive incoming calls on a rotary phone connected to a VoIP line (because the ringer circuit still works on the AC voltage), but you can't dial out. The system has no idea what number you’re trying to call. In some cases, even the ringing may not work reliably due to the lower voltage output of some VoIP adapters compared to traditional landlines. 

The Solutions: Bridging the Gap

Luckily, a few clever solutions have been developed to overcome this technological mismatch.

1. The Pulse-to-Tone Converter.

This is the most popular and straightforward method. A pulse-to-tone converter is a small, external box that sits between your rotary phone and the VoIP adapter. The converter's job is simple: it "listens" for the electrical pulses from the rotary dial and, once it detects them, translates them into the corresponding DTMF tones. For example, when you dial a "5," the converter sees five pulses and then generates the two specific tones for the number 5, sending them down the line to the VoIP adapter. 

These devices are generally plug-and-play, and some are even integrated directly into the phone's internal wiring for a cleaner look. Some converters may also help with ringing issues by providing more power to the phone's mechanical bell. Choosing a Converter: When selecting a converter, consider its features. Some offer a simple pass-through function, while others might have a dialing buffer, allowing you to dial a number fully before the converter sends the tones. This can be useful for dialing special codes or for people who dial more slowly. 

2. A VoIP Adapter with Pulse Dial Support

Some VoIP adapters (also known as Analog Telephone Adapters or ATAs) are specifically designed with a setting to enable pulse dialing. While these are less common, they can be a great all-in-one solution. You would need to check the specifications of the ATA before you buy it, but if you find one (Grandstream ATA's are a good example), it eliminates the need for a separate converter box. You simply plug your phone into the ATA, configure the setting, and you're good to go.

Although you have to do your homework, done correctly this can be a more reliable answer (than a pulse to tone converter)

Pro-tip: Read reviews and forums to confirm that the pulse dialing feature on the ATA works reliably with vintage phones. Not all implementations are created equal, and some may have issues with older, more sensitive equipment. 

Also make sure your VOIP provider allows you to alter the setting inside the ATA so that you can turn on "Pulse Dialling" as this is often turned off by default.

3. DIY and Custom Projects

For the more technically inclined, a DIY approach can be an exciting project. This often involves using a microcontroller, like an Arduino or a Raspberry Pi, to build your own pulse-to-tone converter. This allows for a high degree of customization, such as programming special functions or integrating the vintage phone into a broader smart home system. For instance, some DIYers have rigged their rotary phones to act as a virtual assistant, where picking up the handset automatically triggers a voice prompt. 

How it works: The microcontroller's digital inputs can be configured to detect the voltage drops caused by the rotary dial's pulses. A simple program then counts these pulses and, based on the number, generates the corresponding DTMF tones using a tone-generation library or by manipulating a digital-to-analog converter (DAC). This approach offers maximum flexibility and is a fantastic way to learn about electronics and programming. 

Beyond Dialing: 

The Other Challenges Getting your rotary phone to dial out is a significant hurdle, but it's not the only one. There are a few other compatibility issues you might encounter. Ringing: The mechanical bells in Bakelite phones require a relatively high AC voltage (typically 90V) to ring properly. Many modern ATAs produce a lower voltage (often around 40-70V), which may be insufficient to power the bell. While some converters can boost the voltage, a simple fix is often to add a ringer capacitor in parallel with the phone's ringer circuit. This helps the phone "store" enough energy from the lower-voltage signal to ring the bell. 

Summary

By using one of these methods, you can revive your old rotary phone and enjoy its classic charm while still benefiting from the cost savings and features of a modern VoIP line. It's a fantastic way to blend the past with the present and add a touch of retro style to your home or office. You can see how to modify a rotary phone to make it ring on a VoIP line in this video. Modifying a rotary phone to ring on a VOIP line

Simple Explanation of Pulse Dialling

Over the years many people have asked me for a simple explanation of the difference between the old rotary dial "pulse Dialling" and the more modern push button "Tone dialling" telephones. So to make things easier I have produced a simple short (3 minute) video explaining the difference in layman's terms. Please watch the video below.

I hope this helps make things a bit clearer

200 Series Bakelite Telephones

Model 162 & 232 Telephones

In the late 1930's the 200 series Bakelite telephones were the first British rotary dial telephones to be made out of Bakelite (the original synthetic plastic). Before the 200 series range all old telephones in the UK were predominantly made of metal and wood.

At the time Bakelite was a big improvement as unlike metal the Bakelite Telephone bodies were made of electrically non-conductive material, whilst at the same time Bakelite is very resistant to damage by both by heat (unlike modern plastics) and corrosive liquids such as acids.

Why do you need a Bellset !

When it was first introduced the 200 series Bakelite phone did not contain an integral telephone bell. Back in the 1930's it was still thought to be a good idea to have the telephone bell separate to the main telephone body. So basically you had the "Telephone Instrument" as one item and the telephone "Bellset" or "Bell box" as another. This is explained in far more detail in the following video.

Using the "right" Bellset !

Today these "Art Deco" early antique telephones are regarded as very collectable. However to achieve the maximum desirability it is VERY important to have them paired with the correct "Bellset" or "Bell box".

If you want to setup your own intercom to talk on these classic vintage telephones without an exchange telephone landline please see How to Make Two Landline Phones Work as an Intercom . Alternatively you could use a vintage PABX however that a far more complicated and larger setup.

This matching of "Bellsets is particularly important for a No 162 telephone as the components required for "correct speech" were housed inside the Bellset along with the bells not in the main telephone instrument. Without this speech component (induction coil) it is not possible to restore the 162 telephone to is full potential. In simple terms without the correct bellset No25 poor speech quality and potential interference with other telephones or broadband reliability would be a big issue.

The slightly later (first appeared in 1935) and far more common Model No 232 (200 series telephone) are easier to match up to a bellset correctly as by that point the "telephone instrument" contained all the speech components and the Bellset only housed the bell mechanism.

For the avid collector the 232 telephone should be paired with a (1930's - 1950's) Bakelite Bellset 26 or at an absolute pinch the the older Wooden (1920s - 1930's) bell box 1A. They will technically work OK paired with a modern bell mechanism such as the 1960's metal Bellset 64D but that,s not ideal from a collect-ability point of view, as back in the day they would never have been originally paired together.

If you are thinking of adding one of these wonderful vintage telephones to your own telephone collection please make sure you read the advice given on this blogsite

Bakelite Telephone Restoration

Bakelite Telephones are regarded as Iconic pieces of British History and luckily they can often be restored to 99.9% of their former glory provide the Bakelite is not chipped or cracked.

Although Bakelite is a Brittle material, unlike modern plastics it is very resistant to ageing caused by acids pollutants and (UV) sunlight, making it extremely suitable for almost perfect restoration. You just need "lots" of patience and the know how.


This 60 year old 1953 British Bakelite Telephone (Model Number 314) was restored form its original state, see photograph of this vintage telephone below.

 

Above Fully Restored vintage 314 Phone, Below the same Bakelite GPO Telephone before the restoration process started.

  

The Bakelite Telephone Restoration process can be broken down into three main areas.

• Cleaning and Polishing Materials, such as Bakelite Polish etc, this is 10% of the total process. Paste polishing No 5 was originally used by the GPO back in the 1950's and in our opinion it is still the best Bakelite polish on the market. Luckily it is still available directly from the manufacturer Greygate Chemicals

• Elbow Grease (Physical Effort), this is 40% of the process. However, if you have access to the correct "slow speed" workbench buffing machine this will help speed up the restoration process and provide a much better final finish.

• Time and Patience = 50% of the process. For example the restoration of the Bakelite Telephone above took 9.5 hours of work over a three day time period. Even with the right tools, experience and compounds you are looking at a minimum of 9 hours to restore a Bakelite phone to this kind of near perfect condition.

Below are close up photographs of the vintage telephone restoration in detail. See if you can figure out which ones are the vintage telephone before restoration and which are the ones of the Bakelite phone after restoration :-)

Front View of the vintage Bakelite GPO 314 Telephone, with the rare extra 3 chrome buttons.

The Bakelite Telephone Handset, before and after restoration.

See how shiny and "near perfect" the right side of this beautiful Vintage GPO Telephone looks after restoration.

 

The Classic horn shaped (model no164) Bakelite telephone mouthpiece.

Rear view of the vintage telephone. Notice the lovely reflection in the restored Bakelite.

NO paints, coloured polishes or varnishes were used, the Restored Bakelite telephone is just that. The only extra /new parts used in the above restoration were:

• High Quality British made cotton Braided Handset Cord.
• Metal 314 Badge (Bell On, Call Exchange, Bell Off)
• Replacement Dial Number plate (Very high quality, made in the UK).

We hope this helps or encourages people to restore these iconic antique/vintage GPO telephones. Remember lots of patience is the key.

Bakelite 232 Telephones Insides missing

WARNING, with reference rare 232 British Bakelite telephones like the one in the photograph below there has been a recent trend in a very worrying practice performed by some telephone restorers in the UK. This can be expensive to put right, potentially costing in excess of £60 in labour costs alone. Please see Bakelite 232 Telephone Problem Details

Bakelite 232 Telephone (No Bell Set)

I would urge you to check with whoever you are buying your telephone from that they are not doing this to the telephones as part of the restoration process.

If the speech quality of your 232 telephone is not as good as you think it should be check inside your telephone to make sure you don't have this problem first.

This removal of vital components degrades the speech quality of these telephones by approximately 75%. The telephone will still appear to work however the sound quality, usability, and compatibility with the telephone exchange is significantly reduced.

UPDATE--

It has also been pointed out to me by a colleague that this removal will also cause permanent damage (over time) to the original telephone ear receiver, due to constant DC polarization.

Fitting a British Ericsson Bakelite Black N1071 model Wall phone

Fitting old British Bakelite wall telephones from the 1940's and 1950's can be tricky if you don't know how. This article has been put together to explain the easiest way to fit these classic N1071 model old telephones.

Step 1: Using a flat bladed screwdriver loosen the Bakelite telephone case retaining screw (it only needs loosening not removing). See below.

Step 2: The Bakelite case of the telephone should now hinge out from the metal base of the telephone as shown below.

 This gives easy access to the metal base.

The Base (or wall plate) has three mounting points.

Step 3: Using a pencil mark the wall through these three holes (one at the top and two at the bottom). Making sure the wall plate is level.

Tip: This is a lot easier if you use help, get one person to hold the weight of the Bakelite telephone while you position and mark the holes.

Step 4: Drill the marked holes and use the appropriate screws and if needed raw-plugs for the type wall you as fastening it to.

Step 5: Once the wall plate is securely fastened to the wall, you can simply close the case (making sure you do not trap the wires) and gently re-tighten the case retaining screw as in step1.

You can now make test calls to your Vintage Telephone and make sure it rings correctly etc.

Fitting a 321 Bakelite Wall Phone

How to fit a 321 Bakelite Wall Telephone

1) The first step is to loosen the retaining screw at the bottom of the Bakelite case (using a flat bladed screwdriver).

Bakelite Wall Telephone

2) Next carefully lift the Bakelite case up off the 321 telephone from the bottom and slide the case gently up as shown below. The case hangs on two metal clips at the top of the bakelite case.

3) Note: The Bakelite case is attached to the telephone body via a strap to prevent it falling to the floor and breaking. Do not remove this strap.

4) You can now position your antique telephone against the wall and fasten it to the wall through the four holes in the telephone case, using the appropriate screws as shown below.

Note: Remember to make sure you have a telephone socket within easy reach of the length of the telephone line cord.

5) Use the correct screws and fastenings for the type of wall (wood, plaster, etc)

6) Although there are four holes in the feet of the telephone (two at the top and two at the bottom) you can sometimes manage with three provided the wall is level. However be very careful. If you want to use these wallphones as Escape Room telephone intercoms  there are a number of ways of doing this. One solution is to use a device known as "Exchange in a Box", this is a central “brain,” for two old phones to connected directly together.

7) Once the Bakelite Telephone is securely fitted to the wall you can replace the case on the telephone.

As you can see in the photograph below the bakelite case has two metal clips that fit over the telephone body to "hang" the case on.

8) TIP: Make sure the rubber cable entry grommet for the braided handset cord is located correctly in the Bakelite case as shown below.

9) Finally fasten the retaining screw in the Bakelite base as shown below and plug your line cord into your telephone socket.

10) Provided your Antique Bakelite telephone was restored and converted correctly it should now work and the incoming bell ring should sound fantastic :-)