Touch Tones on AudioCodes Deskphone Not Transmitted Properly to Other End | Community
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Kevster5
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February 14, 2026
Question

Touch Tones on AudioCodes Deskphone Not Transmitted Properly to Other End

  • February 14, 2026
  • 2 replies
  • 24 views

Hello I have an environment with new Audiocodes 445HD deskphones connected to Zoom. Everything is working fine except, when someone presses digits while in a call the digits (touch tones) are not heard/understood on the other end of the phone. So if dialing *86 to get your voicemail you may be asked for your PIN. You press the buttons for your PIN, but the signal is not heard by the voicemail system to access it. If a user dials a bank IVR system, again the touch tones when pressed are not heard. If I dial my cell from the deskphone (while not going through my firewall), I cannot hear the touchtones being pressed on my cell phone end of the call. I have ruled out my Sonicwall as the problem because this model of 445HD has wifi to which I connected it to a mobile hotspot, outside of the firewall. 

I have been researching this like crazy and cannot figure out what the problem could be.

      2 replies

      E
      Community Super Champion | Partner
      Eliot
      Community Super Champion | Partner
      February 16, 2026

      Hi ​@Kevster5 

      400HD Series IP Phone Administrator's Manual Ver. 2.2.16 (M20) - Generic SIP page 82 states support for three DTMF transport modes.  Maybe the wrong was selected. 

      According to Zoom Phone Certified Hardware, current firmware for model 445HD as of 2/16/2026 is 3.5.1.89.  AudioCodes 1/7/2026 Release Notes for 3.5.4.44 firmware, page 3 says Zoom is a supported environment, but says in its What’s New  “Version 3.5.4.44 is not released for Zoom. AudioCodes SIP phones 445HD and C450HD in Zoom environments should continue using version 3.5.1.89.”

      What's new in AudioCodes Generic SIP IP Phones and Gateways devices?

      400HD IP Phone Series Release Notes Ver. 3.5.4.44 - Generic SIP

       

      This phone supports Zero Touch Provisioning (ZTP).  I would expect that Zoom has chosen the correct DTMF transport mode.  Did you use ZTP?

      400HD Series IP Phone Administrator's Manual Ver. 2.2.16 (M20) - Generic SIP

       

      If you have the current firmware on these phones, I would open a support ticket with Zoom support.

       

      In addition, you may want to open a support ticket with Audiocodes.

       

      Thanks, eliot

       

       

       

       

      sparrow
      Community Super Champion | Customer
      sparrow
      Community Super Champion | Customer
      February 16, 2026

      Seems to be a DTMF issue. I don’t have an Audiocodes desk phone to test with, but try looking for DTMF parameters within the phones web interface. Cisco MPP phones are set to default (RFC2833). Check to see if that is the case on your Audiocodes desk phone. If so? Try others one by one, Inband, Info and so forth. If you find no solution, you may want to download the Audiocodes syslog viewer tool from the website and setup the phone to send syslogs to the syslog view tool running on your local desktop. Once running, make a test call and capture the failed digit selection. If you see the digits in the SIP log, you should contact Zoom to show them you’re sending the proper DMFT tones from the device when calling an IVR. 

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