Below are just a few of the boards made by Protel over the years. Most recommended are 7000 (GTE/Quadrum style housing) or 8000 (Western retro-fit), however most of other boards will do the job.

It is a very old Protel board, with old phone voice and no modem, which means all programming must be done at the phone.

Another old board. Early firmware (BB, etc) would not work with 10-digit dialing (not NANP compliant). Later CD/DD firmware should be OK.

Older model but line powered smart board. It uses and old voice prompt and has a 300 baud only modem - can be programmed with ExpressNet software. This board does not have NVRAM and will lose its programming if the phone line is removed as well as the batteries. Accepts DD firmware series so it will work with ExpressNet and current numbering plan.

This board was used in both regular payphones or also what Protel call Semi Private payphones. Can be programmed via ExpressNet, but basic setup can be done with the keypad. The Protel Semi Private Payphone (nice for home use) was used by places that wanted to run their own payphone but did not want to register with the FCC and a utility company. What is the difference with 7000? Probably just the firmware allowing of more options to be programmed via keypad. If so, perhaps 7000 could be easily converted to 310?

We don't know much about this board. It fits the “sentinel” housing (GTE/Quadrum), programming steps are similar to 310 and 7000.

7000c is the Protel's latest model of payphone smart board. The 7000 boards use new English or Spanish voice prompts which the user can change and uses a nonstandard modem to bolster security. In order to program these boards a Protel modem is recommended (due to a non-standard 1200 bps FSK modulation being utilized). A regular modem may work as well, but only at 300 bps. A big plus with the 7000c is flash memory so you no longer have to change out firmware chips and it will retain all setting if loss of power. 7000 can have the firmware updated remotely as well, but only in the RAM - will revert to the old one if a battery dies. Various add-on modules are supported to enable operation on a coin line, use of electronic coin scanners or add a standard 1200 bps DPSK modem. The 7000c allows the use of credit card scanners and LCD or Vacuum Florescent displays. 7000 has two batteries, one 3.6V on the back (14250 type lithium battery) as a backup to retain the settings and rates, and a 4.8V 4x⅓AA rechargeable pack for the regular operation, especially operating the escrow relay. This battery is recharged from the phone line. If both batteries are low, settings and rates may be lost.

The Protel Ascension and Ascension Plus use the 7000c board and allows the installation of a modem on the 7000c board so users could hook their laptop and dial into their ISP (very high tech for its time).

Known issues:

• Always returning coins regardless if the call was answered. Sometimes two clicks of escrow relay are heard.
  Enter diagnostic mode (prog. button until beep, dial 9 0 2), *1 should refund, *2 collect. Operation is reversed.
  Cause: Escrow relay contacts. Red-green wires should go short upon raising the flag but also when the relay is actuated (be careful pushing it by hand).
• No dial tone / appears dead. Check the 3.6V lithium battery (back side of the controller) and 4.8V NiCad battery, and line voltage.

Protel 7000 board with the cover off. Notice the connectors for the add-on boards.

Those boards were made to convert Bell (The Fortress) coinline payphones into a COCOT, or simply update the end-of-life 1D boards (they can work on a regular B1 or Coin line). It fits the standard W/E case to replace the 1C and 1D chassis, supports the ATT 22B coin chute, the mars chute of two different kinds, and the 20A chute from a D set with the electronic coin sensor. It works with the expressnet software.

Both 4000 and 8000 have the same firmware (DD88xx series) and they look identical. We don't have any documents specific for the 4000/8000 - but it seems like the differences are minor and mostly limited to the placement of connectors on the circuit board.

The 8500 chassis fits the same housing but was used in the Protel Acension which had the scrolling graphics and the card reader like the Nortel Millennium. However, Panorama software is needed to make the graphics work.

Main chips - Protel 4000 board:

• G65SC151PEI-1 - main CPU, made by CMD, a specialized Telecommunication MCU based on MOS 6502 (used in many 8-bit computers) with DTMF / modem generator capabilities
  
• M27C2001 - 256kB EPROM, firmware chip (bottom side of the control PCB - not pictured)
  
• HM628128LFP - 128kB static RAM
  
• X28C256D (2 pcs) - 32kB EEPROM, unknown purpose
  
• 73K212L - Bell 212/103 modem (1200/300 bps)
  
• MT8870 - DTMF decoder
  

Protel 8000c has mostly the same chipset, except the M27C2001 EPROM is replaced with a soldered flash ROM and the main CPU is branded Protel, but most likely it's the same product. It's also equipped with a piezo-electric ringer, so either this or a mechanical one can be used. 3.6V lithium battery is not needed anymore as the settings are preserved in the Flash ROM. 4.8V battery is still used to power up the circuitry, especially to operate the coin relay.

Known issues:

• No dial tone / appears dead. Check the 3.6V lithium battery and 4.8V NiCad battery and line voltage.
• No dial tone / appears dead but batteries & line voltage OK. Keypad & handset tested OK with another unit. Reconnect two stacked boards, bad / oxidized contacts. If still not working, re-solder all points on the bottom of the analog PCB (the top board). Most likely cold soldering / bad contact. Fixed two boards this way.
• Electronic coin collector (Mars or AT&T) only works once in a while, most of the coins get rejected, if accepted - still not recognized. I've encountered three cases all with 4000 board (metal), no known solution. Sometimes reprogramming works. Standard mechanical collector (20A) works fine.

Protel 4000 assembly and two of the stacked boards removed from the frame.

Protel 8000c assembly and two of the stacked boards.