In order to process a phonecall correctly freeswitch requires the extension field in the sip_profiles file. The Value has to be set to the phonenumber given to you by sipgate / your provider. See https://github.com/bigbluebutton/bigbluebutton.github.io/blob/master/_posts/2019-02-14-customize.md#add-a-phone-number-to-the-conference-bridge for reference.