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DTMF bleed is the term used to describe short duration snippets of DTMF tones that can sometimes be heard at the call centre side even when a DTMF masking solution is in place. This can occur in some DTMF masking solutions because the algorithm to detect the presence of a tone can take several milliseconds to detect the presence of a tone. During this time the masking solution may not suppress the tone and a small portion of the tone slips through and reaches the contact centre environment. The biggest consequence of this is that when it occurs, the contact centre is brought back in scope of PCI DSS.


If you’re a customer of PCI Pal, the answer is no. Some other DTMF masking solution providers rely on masking the tone only after the DTMF detection algorithm has signalled a tone is present.  PCI Pal uses a “step-back” solution which detects the tone and winds back the stream of audio several milliseconds before masking the audio stream to ensure that the tone is completely masked. PCI Pal’s platform also prevents DTMF duplication errors causing a similar leak of tone-based information through to the call centre. For example, where the DTMF sent by a customer happens as in-band tones and is also erroneously duplicated as out of band messages. Some solutions may mask one type of tone transport but allow the other to pass through and thereby end up in call recordings.

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