I'm getting this problem after installing full version of Zoiper 5 today. No dial tone and no DTMF.
The answer above seems to be to use the dialler from the 'In Call Menu'. However, the 'In Call Menu' does not appear until after the call has begun, using the first number pad. Then the number pad on the 'In Call Menu' is greyed out. As soon as the current call ends, the 'In Call Menu' disappears.
I'm using Zoiper 5.45, Windows 10 64 bit, purchased today.
Please advise how I can get the 'In Call Menu' to appear before I dial?