Can the IOS or Andriod 3CX client be used as a CTI master for GSM calls? We have a customer with low data available so we want to use the data of the GSM for controlling the device. When making or receiving a call this comes over the GSM network but we want to control this call via the 3CX app (transfer, hold, see presence, company contacts etc.) We tested this with the webclient, then we can setup a call (via CallBack) but hold transfer etc. is not available after a call is setup. My idea would be to setup a call via the GSM network and then switch back to the app for controlling this call.