Comdial Impact Phone Troubleshooting: Top 10 Problems

Step-by-step checks for common Comdial Impact and Impact SCS telephone problems
Start by isolating the scope of the problem: one telephone, one office area, one station card, all incoming calls, all outgoing calls, voicemail only, or the entire phone system. The fastest troubleshooting method is usually to compare the affected phone with a known-good Comdial phone on a known-good station port.

This guide applies broadly to Comdial Impact and Impact SCS digital telephones, including display and non-display models. Many Impact telephones operate on Comdial DXP, DXP Plus, FXS, or FXT systems. Exact button labels, access codes, voicemail equipment, and system programming vary by installation.

Identify the Phone and the Host System First

A common source of confusion is calling every installation a “Comdial Impact system.” In many offices, Impact identifies the telephone model family, while the actual PBX cabinet is a DXP, DXP Plus, FX, or another Comdial platform.

What you find What it usually identifies Why it matters
Impact, Impact SCS, 8012S, 8024S, 8312S, or 8324S on the telephone label The phone or endpoint family Useful for user features, handset replacement, display behavior, buttons, and station-level testing
DXP, DXP Plus, FXS, or FXT label on the cabinet, processor, documentation, or maintenance software The PBX platform Required for card replacement, trunk diagnosis, backup, system programming, and cabinet level repair
Voicemail cabinet, PC, hard-drive module, or separate voicemail server The voicemail platform Required when callers cannot reach greetings, mailboxes are full, or message waiting does not clear
Before ordering a replacement: Record the full model number from the bottom of the phone and identify the host PBX cabinet. Similar-looking Comdial phones are not always interchangeable.

Quick Comdial Impact Symptom Guide

Use this table to identify the most likely place to begin. Do not start with programming or cabinet work until you know whether the failure follows a telephone, cable, port, line, voicemail application, or the entire system.

Symptom Likely area to check
One phone has no display, dial tone, or intercom tone Phone, station cable, wall jack, cross-connect, station port, or station card
Phone will not ring but nearby phones do Ringer volume, DND, forwarding, button assignment, hunt group, station programming
Internal calling works but outside calls fail Trunk group, dial-out permissions, route programming, carrier circuit, line card, or service provider
Calls go directly to voicemail Forwarding, no-answer timer, DND, station coverage, voicemail pilot routing, mailbox status
One phone has static, no transmit audio, or no receive audio Handset, handset cord, headset, speakerphone, station cable, or phone electronics
Several phones in one area are dead Shared cable path, punch block, station card, expansion cabinet, local power, or building event
All or most phones are down after a power outage PBX cabinet power, processor boot, UPS, breaker, power supply, expansion cabinet, or carrier outage

Table of Contents

  1. Comdial Impact troubleshooting overview
  2. Identify the phone and host system
  3. Quick symptom guide
  4. No dial tone on one or more phones
  5. Phone does not ring for calls
  6. Cannot make outgoing calls
  7. Voicemail does not answer or message light stays on
  8. Call forwarding or DND is on
  9. Buttons, transfer, hold, pickup, or feature problems
  10. Static, echo, or one-way audio
  11. Display, lights, date, or time problems
  12. One extension is completely dead
  13. Several phones or the whole system are down
  14. Frequently asked questions
  15. Replacement and upgrade options
1Dial Tone 2Ringing 3Calling Out 4Voicemail 5Forwarding 6Buttons 7Audio 8Display 9Extension 10System Down
Impact Phones Station Trouble

1No Dial Tone on One or More Comdial Impact Phones

First, decide whether the problem follows the telephone, the station cable, the wall jack, the PBX station port, or the entire system. A single affected phone is often a local station problem. If many phones are affected, look for a shared card, cable path, cabinet, or power issue.

Check first: Test a known-good compatible Comdial phone at the affected location. Then test the affected phone at a known-good location or station port. This simple swap test often identifies the failed item without changing programming.

Troubleshooting steps

  • Check whether the telephone display is lit and whether the phone provides an intercom tone when INTERCOM or SPEAKER is pressed.
  • Reseat the handset cord and the station line cord. Inspect the modular connectors for damaged locking tabs, loose pins, cuts, pinched cable, or water damage.
  • Compare the affected phone with a nearby working phone. Note whether the failure follows the phone or remains at the original jack.
  • If only one telephone fails at a shared wall jack or patch location, inspect the station cable and building cross-connect before replacing the phone.
  • If the affected phone works at another port but no phone works at the original location, investigate the station wiring, jack, cross-connect, port, or station card.
  • If internal intercom calling works but outside dial tone is unavailable, go to the outbound call section rather than assuming the telephone is defective.
Ringing Station Features

2Comdial Impact Phone Does Not Ring

A phone that does not ring may simply have its ringer turned down or off. It can also be in Do Not Disturb (DND), forwarded, removed from a hunt group, assigned to a different line appearance, or programmed not to receive a particular call type.

Check first: On many Impact LCD sets, ringer loudness can be adjusted while the telephone is idle by pressing VOLUME UP or VOLUME DOWN. The phone normally gives an audible indication of the selected ringer level.

Troubleshooting steps

  • With the phone idle, raise the ringer volume and place an internal test call to the extension.
  • Check the display and feature buttons for Do Not Disturb, call forward, message waiting, or another active status indication.
  • Determine whether the phone fails to ring for internal calls, outside calls, transferred calls, hunt group calls, or only one specific line.
  • Compare the affected station with a nearby working station that should receive the same calls.
  • Verify that the appropriate line, loop, or feature button is assigned to the telephone and has not been changed or disabled.
  • If the extension rings internally but not for outside calls, review line ringing, hunt group membership, coverage, and PBX programming with the system administrator.
Call Routing Outside Lines

3Cannot Make Outgoing Calls

When a Comdial Impact phone can call internal extensions but cannot place outside calls, the telephone is usually functioning. The problem is more likely an outside line, trunk group, dial-out permission, access code, route pattern, carrier circuit, or line card condition.

Isolate the symptom: Record exactly what happens after the user presses a line button or dials the outside line access code. Is there silence, a fast busy, a reorder tone, an error recording, or a call that fails only to certain destinations?

Troubleshooting steps

  • Confirm whether the problem affects one phone, a department, or every phone on the system.
  • Test more than one outside line or programmed line button, if available, and compare results with a known-good extension.
  • Verify the required outside line access procedure for the site, such as selecting a line button or dialing an access code.
  • Check for a station restriction, account code requirement, toll restriction, or changed class-of-service setting.
  • Determine whether incoming calls are also failing. If both directions are affected, inspect the carrier service, trunk card, gateway, or PBX trunk status.
  • Do not change route or digit manipulation programming without documenting the existing configuration and confirming a current backup.
Voicemail Message Waiting

4Voicemail Does Not Answer, Cannot Be Reached, or the Message Light Stays On

Voicemail problems can involve the mailbox, voicemail application, integration ports, call-forward destination, no-answer timer, auto-attendant routing, or storage capacity. First establish whether callers can reach the voicemail pilot number and whether the problem affects one mailbox or all users.

Check first: Place a test call to the affected extension from another internal phone. Let it ring normally, then note whether it rings indefinitely, forwards somewhere unexpected, reaches voicemail, or reaches an incorrect greeting.

Troubleshooting steps

  • Check whether the problem affects one mailbox, one department, or every extension using voicemail.
  • Confirm that the extension has not been forwarded to another destination or put into Do Not Disturb.
  • Verify that the voicemail pilot number or integration path can be reached from an internal station.
  • Check mailbox capacity, message-storage limits, and whether the user can log in and hear messages.
  • If the message waiting light remains on after messages are deleted, follow the voicemail system's documented message-waiting reset procedure rather than randomly reprogramming phone buttons.
  • If all mailboxes fail after a power event, inspect voicemail power, server or module status, and integration with the host PBX before changing individual mailbox settings.
Features Forwarding / DND

5Call Forwarding or Do Not Disturb Is On by Accident

Unexpected call routing is often caused by a forwarding setting, Do Not Disturb, a no-answer path, or a site-specific coverage arrangement. On LCD Impact sets, many forwarding settings can be reviewed through the OPTIONS menu, but the exact choices depend on the telephone model and system programming.

Common clue: If callers say the phone rings once or twice and then reaches voicemail, another extension, or an outside number, investigate forwarding and no-answer routing before replacing the phone.

Troubleshooting steps

  • Look for a CFWD indication, Do Not Disturb status, or a programmed feature button that is lit or active.
  • Use the phone's OPTIONS menu or the site's documented feature procedure to review and clear an unintended forward.
  • Test the extension from another internal telephone after clearing the condition.
  • Check whether the issue applies to intercom calls, prime-line calls, all outside calls, or calls after no answer.
  • If forwarding reappears or the phone was never configured locally, review station programming, coverage paths, and voicemail integration.
  • Do not assume published feature codes are universal. Comdial feature access and button assignments may be customized by the installer or system administrator.
Telephone Features Buttons

6Transfer, Hold, Pickup, Intercom, or Flexible Buttons Do Not Work

Comdial Impact phones use programmable buttons and site-defined features. A button that appears to be broken may instead have a changed assignment, a system restriction, an unprogrammed line appearance, or a feature that is not allowed for that station.

Do not erase button programming first: Compare the phone with a working phone of the same model and user role. Photograph or document existing button labels and LED behavior before changing anything.

Troubleshooting steps

  • Test the feature with a simple internal call before testing an outside-line or carrier-related scenario.
  • Check whether the affected flexible button has a label, LED activity, or a different behavior than the same button on a comparable phone.
  • Confirm the correct procedure in the user guide for the exact phone type: LCD, non-LCD, Impact, or Impact SCS.
  • Compare station class of service, pickup-group membership, and button assignments with a working station.
  • For transfer problems, confirm whether the call can be placed on hold and whether the target extension can be reached by intercom.
  • If several feature buttons stop working at once, investigate system programming, a station database change, or the host PBX rather than individual button switches.
Audio Handset / Headset

7Static, Echo, One-Way Audio, or Poor Call Quality

Audio symptoms should be separated into handset, speakerphone, headset, internal-call, and outside-call problems. If the fault occurs only on one phone, test local equipment first. If it affects many phones or only calls over a certain service, investigate the PBX, trunk, gateway, carrier, or network path.

Fast isolation test: Make one internal intercom call and one outside call using the handset, speakerphone, and any connected headset. Note exactly which combination produces the problem.

Troubleshooting steps

  • Reseat or replace the handset cord and test with another compatible handset if available.
  • Disconnect headsets, adapters, recording devices, and other accessories temporarily to rule out a local accessory fault.
  • Compare handset and speakerphone audio. If only one audio path fails, the phone or accessory is more likely than the trunk service.
  • Check whether the issue affects internal calls, outside calls, one outside line, or only calls to a particular destination.
  • If multiple users hear static or dropped audio, inspect trunk/circuit status, gateway behavior, carrier reports, and any recent network or service-provider changes.
  • For IP or SIP gateway integrations, have a qualified technician check packet loss, jitter, firewall behavior, media routing, and QoS rather than making blind changes at the phones.
Display Phones LED Indicators

8Display Is Blank, Buttons Flash, Date/Time Is Wrong, or Lights Behave Unexpectedly

A blank display on one Impact LCD phone usually points to the phone, station cable, or port. Flashing LEDs may be normal indications of ringing, held calls, messages, or programmed line status. Incorrect date and time are generally controlled at the host PBX, not at each individual telephone.

Document before resetting: Take a photo of the display, button LEDs, and any error message. It helps distinguish normal status indications from a true station or system problem.

Troubleshooting steps

  • Check whether the phone has a display but no dial tone, or whether the entire phone is dead. These are different failure patterns.
  • Test the phone at a known-good station port and test a known-good phone at the affected station port.
  • Review which buttons are flashing and whether the phone is ringing, has a held call, has voicemail, or is part of a programmed line appearance.
  • Compare the affected phone's LED pattern with a working phone of the same model.
  • If all phones display the wrong time or date, use the correct system-level administration procedure for the identified PBX platform.
  • If a display remains blank after a successful port swap, the telephone may require replacement or professional repair.
Station Failure Wiring / Port

9One Comdial Impact Extension Is Completely Dead

A completely dead extension means the phone has no usable display, intercom tone, or response. The most useful question is whether the failure follows the phone or stays with the location. Do not order a replacement handset until this is known.

Best practice: Use a known-good compatible Impact phone and perform a two-way test: good phone at the failed location, then failed phone at a good location.

Troubleshooting steps

  • Inspect and reseat the station cable at the telephone and wall jack.
  • Test a known-good compatible phone at the affected jack.
  • Test the suspected failed phone at a known-good jack or station port.
  • If the failure follows the phone, verify model compatibility before replacing it.
  • If the failure remains at the location, inspect the jack, station cable, cross-connect, patch block, station port, and associated card.
  • If multiple adjacent extensions fail, treat the event as a shared wiring, card, expansion-cabinet, or system problem instead of a single telephone failure.
PBX System Multiple Extensions

10Several Phones or the Entire Comdial System Are Down

When many Impact phones fail together, the root cause is usually not the phones themselves. Focus on the shared PBX environment: utility power, UPS, cabinet power supply, processor boot state, expansion cabinet links, station cards, carrier service, or damage affecting a shared cable route.

Protect the system: Do not repeatedly power-cycle a legacy PBX. Record LEDs, alarm indications, cabinet status, weather or power events, and the number of affected phones before restarting equipment.

Troubleshooting steps

  • Determine the scope: all phones, one floor, one cabinet, one department, one station card, only outside lines, or only voicemail.
  • Verify the AC outlet, breaker, UPS, surge protector, cabinet power cord, and visible power-supply indicators.
  • Check whether the PBX processor and any expansion cabinets have completed a normal startup sequence after a power event.
  • Check whether outside telephone service is present at the provider demarcation point if inbound and outbound calling are both affected.
  • Record cabinet model, processor type, software release, cards, alarms, and any recent utility, network, construction, or carrier changes before calling for service.
  • For suspected hardware failure, overheating, burning odor, water exposure, or a repeating power alarm, leave the affected equipment powered down and arrange qualified service.

Comdial Impact Replacement and Upgrade Options

Comdial Impact and Impact SCS phones remain in use at many small and mid-sized businesses, but the equipment is legacy technology. A single failed phone, cord, station port, or card can often be repaired with compatible refurbished equipment. Repeated failures, unsupported carrier interfaces, voicemail problems, or a lack of qualified service may justify a planned replacement instead of ongoing emergency repairs.

Before replacing phones or the entire system, document the exact telephone models, host PBX cabinet, number of users, outside-line type, voicemail operation, paging, door phones, fax or alarm lines, call accounting, and any business-critical integrations. This prevents a replacement project from overlooking functions that have accumulated over many years.

For a compatible system expansion, replacement phone, modernization plan, or complete phone-system quote, use the business phone system quote request form.

Frequently Asked Questions

Why does my Comdial Impact phone have no dial tone?

If one Comdial Impact phone has no dial tone, first determine whether the problem follows the phone, the station cable, the wall jack, or the PBX station port. Test a known-good compatible phone at the affected location and test the affected phone at a known-good location. If several phones are dead, investigate the PBX cabinet, station card, cabinet power, or an affected building area.

Why is my Comdial Impact phone not ringing?

Check ringer volume first. Also check whether Do Not Disturb, call forwarding, a changed line-button assignment, hunt-group settings, or station programming is preventing the extension from ringing. If the phone rings for internal calls but not outside calls, the problem may be line appearance or PBX programming rather than the telephone.

Are Comdial Impact phones the same as a Comdial DXP or DXP Plus system?

Not necessarily. Comdial Impact and Impact SCS generally identify telephone families. Many Impact phones are used on DXP, DXP Plus, FXS, or FXT digital communications systems. Identify the cabinet or control unit before following system-level programming, card replacement, backup, or repair procedures.

What should I do before replacing a Comdial Impact phone?

Confirm the full telephone model number, host PBX platform, installed station-card type, and software release where applicable. Test the suspected phone on a known-good port first. A similar-looking Comdial phone may not be electrically or software compatible with the existing system.

Can I reset a Comdial Impact phone by unplugging it?

Disconnecting and reconnecting a single telephone can help confirm a loose connection or temporary station issue, but it will not fix a defective station port, failed card, incorrect PBX programming, trunk outage, or voicemail-server problem. Avoid unplugging multiple phones or repeatedly restarting the PBX without first documenting the outage.