'realm' value to use in the Telephony Gateway config

[zetronuser]

Hello,
We are trying to configure an Asterisk-based Telephony Gateway to connect an on-prem Windows instance of the 3cxPBX system. We are not sure what 'realm' value to specify in the Telephony Gateway's config (see attached screenshot). We have tried '3CXPhoneSystem' and it does not seem to work for us. Any guidance here would be much appreciated.
Thank you.

 

[xcobean]

Hello,

This ideally should be the IP of the server you are connecting to.