Advanced - Behavior (Tab) - Phone Behavior (Section): Block URL Dialing
You can block the dialing of SIP URLs via PUI and WUI (phone & web user interface) by turning this setting on or it can be limited to PUI only with value: pui. In both cases only numeric numbers will be allowed as input.
<on>, <off>, <pui>
on (since version 184.108.40.206)
pui (since version 10.1.41.0)