DTMF Not Being Honored
If you have a caller on a call on Line 1, and you press line 2 to make a new call, you may notice that the conference of the calls and DTMF function is not respected. While this function worked fine in version 16, it does not work in version 18.
The conference function for all bvoip softphone clients and Snom IP-based phones will use the phone system conference function. With version 18, it is considered expected functionality for DTMF tones to not be acknowledged by the phone system managing the conference.
Phone Specific Issues
One caveat that may cause confusion is the use of certain IP-phones, such as most Yealinks and three-way calls attempting using this feature. These type of conference calls made by those IP-phones, even with additional lines available, may be managed directly by the phone and provide DTMFs to the third called party for a conference, which are not honored.
The Workaround for Phones
The workaround for DTMF not being supported is to open a new line while on a call outside the conference, and after the DTMFs are used to reach the destination for the second call, then transfer the second call to the conference.
Supported Method
Place the DTMF call as new and outside of the conference. After reaching the party, use the DTMF and transfer them into the conference call related to the extension with the default dial code: 700** followed by the extension number.
For more information on dial codes, please see our Dial Codes article.