Recording DTMF Muting explained: hiding card numbers for PCI

If a customer keys their card number into the phone during a call, those tones land in your recording unless you stop them. Recording DTMF Muting is the feature that stops them. It watches for keypad tones during an active recording and, the moment it hears the first one, it blanks the audio for a number of seconds you choose. The card number is entered, the system reads it, and the recording stays clean.

What the setting actually does

DTMF is the technical name for the tones a phone keypad makes. Each digit has its own tone, and a recording captures those tones as plainly as it captures speech. Anyone who plays the file back can decode them. That is the problem DTMF muting solves. When the feature is on, the system mutes the recording for the number of seconds you set after the first DTMF signal is detected while recording is active. Set it to 0 and the feature is off. Set it to 20 and you get a twenty-second window of silence starting at the first tone, which is usually enough for a customer to enter a card number, expiry, and security code.

There is a second switch that has to be on for any of this to work. The campaign value only takes effect if the Allow Recording DTMF Detection system setting is also enabled. That system flag turns on tone detection for the whole platform; the per-campaign number decides how long to mute once a tone is heard. Both have to line up.

Why this matters for PCI

Card data that ends up in a stored recording pulls that recording into PCI scope, which means tighter storage, access, and retention controls on every file. Muting the tones at capture time is cleaner than scrubbing files later. If the digits never reach the file, the file is not card-bearing in the first place. That is the whole appeal of DTMF muting for payment handling, and it pairs naturally with a sensible PCI pause workflow where the agent steps back while the customer keys their details.

flowchart TD
  A[Recording is active] --> B{System DTMF detection on}
  B -->|No| C[Tones recorded as audio]
  B -->|Yes| D{Campaign mute seconds above zero}
  D -->|No| C
  D -->|Yes| E[First keypad tone heard]
  E --> F[Mute audio for set seconds]
  F --> G[Recording resumes clean]

Scope and gotchas

The campaign setting only covers calls placed from that campaign. Inbound traffic is separate: if you want the same muting on calls that come through an In-Group, you enable the feature on each In-Group as well. A campaign that handles both directions does not cover its inbound legs just because the campaign value is set. See DTMF muting for inbound groups for the inbound side.

One behavior catches people out: turning on Recording DTMF Muting for a campaign automatically disables the agent-clicked Mute Recording button there. The two are not meant to run together, so you pick one model. Automatic tone-triggered muting is the right call for payments because it does not depend on the agent remembering to press anything. The window is fixed, so size it to the longest entry you expect rather than the shortest, since the timer starts at the first tone and does not extend if the customer pauses.

DTMF muting is one piece of a larger recording strategy. For how it fits with capture modes, storage, and retention, start with our call recording guide. When you are ready to run payment-safe recording without stitching it together yourself, check our pricing to see how quickly it can be live.