We are having an issue with registering FXS 24/48 port ATA’s to our SIP server which appears to be an issue with their FQDN having an underscore. (ex. bobs_pbx.example.com) Has anyone else run into this issue and is there any way around this? Our customer’s PBX has several hundred extensions/endpoints and rebuilding their domain without an underscore is not an option. We are able to register to any other FQDN without an underscore and we are not able to replicate the issue on a different device from another manufacturer. Any help or suggestions are greatly appreciated. Thank you kindly.