Hey! Yeah, the realm can definitely be set to match the Termination URI, but it's a bit tricky depending on your SIP stack and how your auth handlers are configured. The challenge is getting the realm to dynamically pull from the request context rather than a static config value. There are a few different approaches depending on whether you're using Asterisk, FreeSWITCH, Kamailio, or something custom-built. What's your current setup? Happy to point you toward the right solution - I've dealt with this exact scenario in multi-tenant environments before.