Call Controllers
TC100 CPC Signal Generator
$58.95
Open-loop disconnect generator that forces a clean hang-up on lines that don't natively supply a CPC signal.
Volume discounts available — request a quote for pricing on bulk orders.
The CPC Signal Problem
A CPC (Calling Party Control) generator—also known as an open-loop disconnect generator—is a hardware device that forces telephone equipment to hang up by momentarily breaking the loop current, typically for 500–1000 ms, once a call has actually ended.
On a traditional POTS (Plain Old Telephone Service) line, this happens automatically: when a caller hangs up, the central office briefly cuts the DC loop voltage (typically dropping 48V to 0V for ~300–800 ms). That voltage drop is the CPC signal, and it tells automated equipment to hang up.
The Gap: Legacy analog PBX stations, VoIP ATAs, T1 channel banks, and certain central office or off-grid lines often don’t supply this signal at all — they just leave a busy signal or dead air on the line. Without a real CPC break, downstream equipment never gets the cue to hang up, which leaves ports locked or recordings running indefinitely.
The TC100 CPC generator sits inline to close that gap. It monitors the line for the busy, reorder, and silence patterns that stand in for a real disconnect, and when it recognizes one, it manually opens the loop for roughly 500–800 ms — long enough for downstream equipment to read it as a genuine CPC signal and hang up.
Typical Applications
1
Voicemail Systems Behind PBX / KSU
The Issue: When a far-end caller hangs up, an analog PBX extension connected to a voicemail system often receives continuous dial tone, busy tone, or reorder (fast-busy) tone rather than a physical disconnect signal. The voicemail system continues recording dead air or tone audio.
CPC Generator Solution: Monitors the line for busy tones, dial tones, or silence, and triggers a loop-current break so the voicemail system instantly hangs up and releases the port.
2
Automated Attendants & Call Sequencers / ACDs
The Issue: Automated Call Distribution (ACD) units, call sequencers, and auto-attendants keep ports locked “in-use” if they do not receive a CPC signal when the caller drops.
CPC Generator Solution: Ensures immediate line clearing so auto-attendant channels become available instantly for the next incoming call.
3
VoIP Gateways & ATA Adapters
The Issue: Many Analog Telephone Adapters (ATAs) and VoIP modems/gateways convert digital SIP channels to analog lines without properly generating an open-loop CPC signal when a SIP call terminates.
CPC Generator Solution: Placed inline on the ATA’s FXO/FXS port to detect audio signal termination (busy tone/silence) and generate the missing loop break.
4
PBX Tie-Lines & Tandem Configurations
The Issue: When routing station-to-trunk calls across two interconnected PBX systems (tandem PBX setup) or through station-to-station extension paths, CPC signals from the phone company are lost.
CPC Generator Solution: Regenerates the disconnect pulse between PBX trunks so multi-site tie-lines don’t stay locked open on dead channels.
5
T1 / E1 Channel Banks
The Issue: Analog station cards in T1 channel banks frequently pass audio without providing loop-current interruption upon far-end disconnect.
CPC Generator Solution: Adds CPC disconnect signaling to T1 channel bank lines feeding legacy voice processing equipment.
6
Answering Machines & Emergency Dialers
The Issue: Standalone tape/digital answering devices, automated alert dialers, and security control panels on lines lacking central office CPC will fail to reset after a call finishes.
CPC Generator Solution: Detects silence or return-to-dial tone and breaks the current so the dialer or answering device resets for future triggers.
7
Central Office (C.O.) Lines Lacking Native CPC
The Issue: Some rural or legacy telco switches (or ISDN terminal adapters) do not have CPC/open-loop disconnect enabled or supported on their analog loops.
CPC Generator Solution: Serves as a retrofit solution to generate a standard 1-second CPC pulse locally without having to upgrade or request switch-level reconfiguration from the service provider.
Specifications
| Model | TC100 |
|---|---|
| Function | CPC (Calling Party Control) Signal Generator |
| Detected Tones | Howler, Dial, Busy, Reorder, Silence |
| Open Loop Duration | ~800 ms |
Programming
Lift the receiver and dial #0* within 3 seconds to
enter programming mode. Each register is set by dialing its
two-digit number, the value, then ## to confirm. If
you wait longer than 3 seconds after going off-hook, the TC100
assumes you’re done and switches to normal tone-control
operation.
Registers
| Register | Function | Default | Valid Range |
|---|---|---|---|
| 01 | Cadence On Time (ms) | 4000 | 1–20000 |
| 02 | Cadence Off Time (ms) | 0 | 0–20000 |
| 03 | Cadence Tolerance (ms) | 0 | 0–500 |
| 04 | Cadence Matches | 1 | 1–20 |
| 05 | Frequency Watch Mask | 10100000 | 8-digit mask |
Register 05 is an 8-digit mask, one digit per frequency, in this
order: 350, 400, 440, 480, 620, 1400, 2060, 2600 Hz. Set a digit
to 1 to watch that frequency or 0 to ignore
it.
Programming Examples
Detect a 400Hz tone lasting at least 1000ms
#0* enter program mode
01 1000 ## set duration to detect
02 0 ## cadence off time = 0 (tone-on only)
03 0 ## no cadence tolerance needed
04 1 ## match one time
05 01000000 ## match 400Hz onlyDetect a busy tone (480Hz + 620Hz, 500ms on/off)
#0* enter program mode
01 500 ## set cadence on time to detect
02 500 ## set cadence off time to detect
03 50 ## tolerance ±10% (50ms)
04 4 ## match 4 on/off cycles
05 00011000 ## match 480Hz and 620Hz componentsDetect 4000ms of silence
#0* enter program mode
02 4000 ## set cadence off time to 4000ms
03 0 ## no tolerance
04 1 ## match one time
05 00000000 ## disable all frequency componentsDocuments
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