disable “only permit incoming call”
V19 is updated to support some new features in external line. We add a new item “maximum simultaneous outgoing call” in “outgoing call” tab.
This new item can limit how many concurrent calls can be processed by the external line. It it is configured to be zero, that mean the line cannot make any outgoing call.
That also means previous item “only permit incoming call” is unnecessary, so we cut this item together.