VOIP Ready 'Call Exchange' 312 GPO Bakelite Telephone- for all domestic VoIP services.
Supplied with our own inDAT Pulse to Tone converter to give you tone dialling and, if you require, 'Star', 'Hash', 'Last Number Redial' and up to seven stored numbers. These options are switchable so the telephone can quickly be customised to your needs.
Developed with Geoff Peters, the inDAT is an internal pulse to tone converter that is near silent in operation. It is designed to function on traditional copper telephone lines, all domestic VoIP lines (BT Digital Voice, EE, Sky etc) and external ATA's. It is not suitable for use on Digital Business lines without an external ATA.
About the telephone
This is a lovely example of a British Bakelite 312 'Call Exchange' introduced by the GPO in 1949 and used on 'Shared Service' or 'Party' lines. The telephone is in first class working order and the case has a nice sheen. It also has a fully serviced No.12 dial with an alphanumeric dial plate. The handset is marked 1956 (164 56). All cords have been replaced with my own, UK manufactured, pure Egyptian cotton braided cords correctly terminated with cotton ties.
It comes complete with our own high quality reproduction paper furniture. The dial label can be customised with an area and telephone number of your choice.
Our full, top quality restoration includes:
- Our own quality cotton line and handset cords
- High quality replacement transmitter unit
- Fully serviced dial
- Quality replacement furniture
- Mechanically polished case
- Quality replacement feet
Restoration Details:
•Handsets and cases are stripped of their components and thoroughly cleaned.
•Cases are polished, both mechanically and by hand. It has taken me many years to perfect this technique and it will return the case to the best possible condition. Polishing by hand alone will not achieve the best results.
•All contacts are cleaned, set and polished.
•Dials are stripped, cleaned, inspected, lubricated and rebuilt. This includes the removal and cleaning of the governor, governor cup and main bearing. The contacts are set and the dial speed and MK /BK ratio set. This is an essential part of making a telephone work properly.
•Bell coils are set and any necessary adjustment made so their resistance is suitable for modern networks.
•A new line cord is fitted and the telephone is reassembled with the appropriate wiring alterations made to allow it to function on a pulse dialling system.
•Mouthpiece are fitted with a modern electronic transmitter to provide high quality speech.
•Finally, telephones are tested on a live line to ensure they are working correctly and a custom dial label is fitted.
About our inDAT
This is another product we produced because we were not happy with the performance of other similar products on the market.
Because we know a lot of our customers like vintage telephones to be kept as original as possible, our inDAT can operate in one of three modes.
1) Pulse to tone conversion only – dialling 0-9.
2) Pulse to tone conversion, 'Star' & 'Hash'.
3) Pulse to tone conversion, 'Star & Hash', 'Last Number Redial' & Stored Numbers.
Our inDAT is fitted internally. It is a single unit and requires no addition components.
Technical Notes
The inDAT has full bridge rectification to protect against reverse line polarity. It needs 24mA to operate which is matched or exceeded by all common VOIP services.
It has a balancing circuit to work with most types of microphone - carbon or electronic.
Once a dialled digit has been detected, the circuit will send out a corresponding tone burst to line using DTMF4 encoding. To solve the noise issue we have a muting device to attenuate the tone to an almost inaudible level.
Because of the current draw, the inDAT cannot be used in a circuit that has a Dial-A-Tone before it in the circuit. Rearranging the order of connection will resolve the issue.
Note: Because of variance across the new VOIP market, we supply all inDAT installations with a BT to BT ring capacitor adaptor. This will allow telephones to ring in all VoIP connections that do not have a ring capacitor, but should not be used unless required. Please contact us and we will explain – it’s very straightforward!
