You’re definitely not the only one—this happens a lot when using SIP providers outside Twilio, Telnyx, or Vonage with Retell. Most of the time, it’s related to authentication, codec compatibility, missing SIP headers, or NAT/firewall routing. Retell is more optimized for the major providers, so other trunks usually need extra configuration to work properly. It can also show up as failed registration, dropped calls, or one-way/no audio. Which provider are you using, and where exactly are you getting stuck right now? @joshuanellson