Starting from 2N OS version 2.44, 'Local Calls' have to be enabled in order to call other 2N devices in the device:device_ID format. The Local Calls feature has been disabled by default for security purposes and needs to be enabled manually on both the Intercom and indoor answering units
https://www.2n.com/en-AU/manuals/35318/2_45/local-calls/
Indoor View - Enabling Local Calls
IP Style (Intercom) - Enabling Local Calls
Refer to below link showing how to setup local calling
https://wiki.2n.com/faqint/en/how-to-set-up-calls-from-to-2n-ip-intercoms-104868074.html