Hello! We have problems with DTMF tones on Snom D715, D765 and D725 phones. At irregular intervals, the Snom phones stop sending DTMF tones. Firmware on the devices is the 3CX version 18.104.22.168 After a restart, the problem is gone for a short time. But comes back at irregular intervals. Are there any solutions? We also unse the Snom DECT M700 system. DTMF here works perfect.