Mountain Electric

Coin Lines & Trunks

PhreakNet is home to fully functional authentic coin lines and trunks, intended for network-controlled payphones (as opposed to COCOTs, which handle their own billing).

Lines and trunks are available for virtually every single kind of payphone that existed/exists in the North American network.

The PhreakNet coin trunks are not a mere simulation. They adhere to the specifications used for network-controlled coin signaling and are intended to be used with real or compatible equipment. Expanded In-Band Signaling is used exclusively; multiwink signaling is not supported. The only deviation from these is that if a system-hosted line is used, detection of the initial deposit is done by using the coin denomination tones as opposed to an actual ground test (which is a bit difficult to do over the Internet, needless to say). However, you can use your Class 5 coin equipment and only use PhreakNet for handling toll calls. In this case, there would be no deviations from authentic design and operation.

Support for coin phones on PhreakNet is modular and flexible. The system is composed of seven major components:

Adjunct systems such as PhreakNet TSPS (0+ dialing) and operator services are not explicitly included here, but are tied into the system.

The system is modular as most of these components are relatively isolated and only interact with other components through special interfaces. This modularity means that different components can easily be swapped in or substituted.

The main modularity in the system is the distinction between Class 4 and 5 components. The PhreakNet coin trunks (Class 4) do not have a dependency on the PhreakNet coin lines (Class 5). This means you can connect your existing coin equipment (whether electromechanical, e.g. SxS or digital, e.g. Redcom) and integrate it with PhreakNet TSPS for handling toll calls. You can have outgoing toll calls either go to Coin Zone (for human operator handling) or ACTS (for automated handling). Additionally, 0+, third-number, calling card, and operator services are available through the coin lines and trunks, just as they are on PhreakNet generally.

PhreakNet coin lines use PhreakNet coin trunks for handling (though note the reverse may not necessarily be true). Several variations exist to allow calls to be made through both Coin Zone and ACTS.

The major types of local coin control are:

A good introduction to local coin control is provided in this Evan Doorbell tape. With the exception of postpay service, the major types of coin service are all discussed here.

The two types of remote coin control used are:

Both systems use Expanded In-Band Signaling only. Multiwink signaling is not supported.

Miscellaneous notes about operation:

Demo Lines

Virtually every kind of coin line in existence is supported. The following demo lines may be used to interact with the system. These are PhreakNet coin lines which use the PhreakNet coin trunks for completing non-local calls.

These are the most frequent method of use by the general public — however, if you are looking to integrate your coin equipment with PhreakNet TSPS, you should directly interface them using a Feature Group C trunk, rather than using a demo line.

Hosted users are eligible to have their line class code (LCC) to be changed to 1PC (1-party coin) for coin service. This puts the line itself in coin mode, offering a full coin experience. The default mode is dial-tone first, but other types of lines are also supported on-demand. Just call the Business Office.

Line Type Toll Provider Demo Line Access # Historical Usage & Other Notes
Prepay (Coin First) Coin Zone 950-0901 This was fairly typical of coin phones in the Bell System, especially into the early 1970s.
Prepay (Coin First) A.C.T.S. 950-0900 I don't think prepay was ever historically used with A.C.T.S., but this is technically possible, so here it is. Postpay phones are fundamentally incompatible with A.C.T.S. so that is not an arrangement that exists.
Postpay (WECo) Coin Zone 950-0908 This is the kind of postpay used in the Bell System, when present (post-pay itself was rare in the Bell System). When a local call is answered, a loud tone impedes the call until the initial deposit is made.
Semi Postpay (AECo) Coin Zone 950-0909 This is the kind of postpay associated with Automatic Electric, very common with independent phone companies. When a local call is answered, the caller is muted until the deposit is made. (Yes, this means you can call things like Time & Temperature at no charge.)
Semi Dial Tone First Coin Zone 950-0905 This is quite rare and is associated with G.E./the General System. It is a hybrid of prepay and dial tone first. You get a dial tone when you pick up, but calls cannot be made until a coin is deposited (including free calls). So it sounds like dial tone first but works more like prepay.
Dial Tone First Coin Zone 950-0903 This is your average early 1970s coin phone — dial tone first operation, using Coin Zone for completing calls that require more than the initial deposit. No coin required for free calls. However, other calls require the initial deposit be made before dialing the number.
Dial Tone First A.C.T.S. 950-0904 This is your average late 1970s coin phone — dial tone first operation, using the Automated Coin Toll System for calls that require more than the initial deposit.

Coin FAQ

Who can use the system?
In short, anyone! There are three major ways to use the system, in increasing order of authenticity:
  • Use one of the demo access lines. If you have your ATA or channel bank/Asterisk off-hook auto-dial a demo line, then you can pretty much use the demo line like the real thing. The only thing that is missing is there needs to be some way for the system to send +/- voltage and reverse polarity on your line.
  • Use a hosted PhreakNet coin line. These are PhreakNet hosted lines with a line class code (LCC) of 1PC (1-party coin). The line is configured as a coin line in the switch. The main void here is similar to with the first method; coin signaling is completed via Feature Group C between the toll office and the local office, but the signaling needs to be extended between the local switch and the physical payphone itself. We are currently working on potential out-of-band solutions to do this.
  • Use the PhreakNet coin trunks with your own coin lines. If you have your own local coin equipment, you can interface with PhreakNet TSPS via Feature Group C trunks. This will provide the most authentic experience.
What's the issue with signaling for collect and return?
"You can't send 130 volts over the Internet." Collect and return can't be done just over IP — there needs to be a physical interface to the payphone itself. This poses some challenges with distributed VoIP architectures. There are some projects out there that provide simple coin line interfaces for Asterisk, but this requires a physical connection to the Asterisk system. A complete interface will require a method of connecting such a circuit to the Internet and enabling at least undirectional communication from the switch to the circuit in order to execute the necessary operations (coin collect and coin return, in this case; initial rate and stuck coin tests aren't used by the PhreakNet coin lines, so these functions are not important).
What is the difference between Class 4 and Class 5?
A class 5 switch is an end-office which directly serves subscribers. A class 4 switch is a toll tandem which aggregates calls from multiple class 5 switches. In the Bell System, functions such as TSPS, ACTS, and other centralized operator services for coin phones were typically located at class 4 switches, not class 5 switches. The class 4 switch uses Expanded In-Band Signaling over a Feature Group C trunk to tell the class 5 switch what to do when needed.
What phones are supported?
In theory, the system is intended for use primarily with single-slot network-controlled coin phones. A.C.T.S. is only compatible with single-slot phones. Coin Zone has partial support for 3-slot phones. 3-slot phones are not supported by PhreakNet coin lines currently — you need to have your own coin equipment (which would detect a ground when the initial deposit is made) for handling local calls, but you may utilize the PhreakNet coin trunks for the Class 4 side of things.
Standard coin denomination tones are required (1700+2200 Hz) — this encompasses virtually all network-controlled coin phones.
In practice, the system may be accessed and used simply by using a red box, even if you do not have a coin phone with a totalizer.
What coins are supported?
U.S. nickels, dimes, and quarters are all supported. Nickels and dimes work best, but quarters may also be used.
What is Coin Zone?
The best information about Coin Zone is in Evan Doorbell's narrated tape discussing it.
Who are the Coin Zone operators?
Coin Zone is staffed by PhreakNet operators. Additionally, the service is staffed 24/7 so Coin Zone calls will always be handled promptly.
Any PhreakNet member interested in becoming an operator is eligible and encouraged to apply. Call the Business Office for details.
What is the history of this project?
This system has had several predecessors and previous iterations which led up to this. Past iterations have not been authentic coin lines and trunks but more of a demo system or simulation. Each iteration has been a complete rewrite from previous systems, and the current iteration is an authentic line and trunk interface that may be integrated with real (physical) coin equipment.
How much work has gone into this project?
On the order of hundreds (thousands?) of man hours over multiple years. This has been one of PhreakNet's primary projects since 2019. If you find the system useful and would like to support it, donations are greatly appreciated. Thanks!