Jump to content

CS410 and Yealink T20P touch tone problem on PSTN gateway outbound call


Recommended Posts

We also have another problem involving touch tone on outbound calls to PSTN trunk for the same setup of CS410 and 4 Yealink T20P Handset. Internally, we are able to use the button to select options in the IVR menus to access voice mail and other functionality within the CS410 PBX. An audible sound is heard when a number key is pressed for internal functionality within the PBX. However, when we making an outbound call through the PSTN trunk to access another PBX IVR menu ( for example: welcome to.. press 1 for sale 2 for support etc....). If I try to press number 1 key for sale option then there is no audible sound heard on the handset and the PBX at the B end could not recognised the selected option. It look obviously to me that some how the PBX could not send the touch tone option to the B end through the PSTN line. Is there any setting that could modify this compatibility issue as it look like country dependent (AUSTRALIA - GMT +10). Thank you very much for your help.

Link to comment
Share on other sites

We set "Trunk requires out of band-DTMF tones:" to NO in the trunk settings for all US installations....


also the "Inband DTMF detection:" settings in Admin general SIP settings is set the ON


I have checked the configurations. Both of these setting are set to NO and ON by default from the factory. Is there any other configurations that we have missed?

Link to comment
Share on other sites

Does that PSTN gateway (what type is it BTW) support DTMF? Maybe you need to get a Wireshark trace to see what exactly is going on. It could be a problem of the gateway, not the phone.


We have found that this is a bug from the latest firmware release ( on reversing to the previous firmware version ( The touch tone F is working fine with its default setting

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...