Showing results for 
Search instead for 
Did you mean: 
Walkthrough Wednesdays

Sustained DTMF Tone

Is there a way to make the 794x phones generate a sustained DTMF tone? For example, I need the "*" key to generate a constant tone for 650ms; however, it is only generating a 10 to 20ms tone even though I'm depressing the key. Thanks.


I haven't seen any new problem caused by TCL/IVR scripting so far, be that Cisco-supplied or other properly written scripts.

But I have seen them doing cool things like delivering ANI on CAS circuits, recording prompts directly from any phone, handle internal and external calls in different ways, dialing with pauses and more.

All things that a $300 PBX does without a problem, but Cisco mysteriously doesn't. Fortunately TCL/IVR is a great solution for many issues.

On the other hand I've seen many voice (and data) network to be brought to their knees by buggy Cisco software.

I do not think that changing the default digit duration is a good solution, becuase that would change it for all calls, eg to enter a 16 digits credit card number would take 10 seconds, making all operations awkward.

Can you please explain your comment to change DTMF durations for your calls? I am using H323 gateways, and I can't seem how to do it for a PRI interface. There are a few commands for E&M, FXS and FXO interfaces, but not for ISDN PRI voice ports. Thanks, Tim

For H323 you will want to change it on the device sending the digits. The h245 methods use include a parameter for digit length. If you have CUCM, there is a service parameter for this if you search for it.


Changing the H225 DTMF Duration service parameter did not make any difference. The H225 DTMF Duration specifies the duration of outbound DTMF digits for H.323 devices.

If your gateway is H.323 then it should take effect - I've confirmed that in the lab before for similar issues.


Do you recall the command?


CUCM has this service parameter that I've confirmed works with gateways:

H225 DTMF Duration

Default is 100ms.


Content for Community-Ad

Spotlight Awards 2021