[SR-Users] Regretfully we were unable to process the URI

Hi Everyone, Very new to SIP And to Kamailio Configuration / administration. I have a working AWS instance with Kamailio installed on it - and it works fine. We are creating a whole new environment and I have cloned the existing AWS EC2 instances. I have edited all the configs to ensure that they are using the correct DNS names and / or IP addresses. Otherwise the "configs" are identical. While attempting to call a SIP number, I get the following message, returned to the soft phone I am using (microSIP) *Regretfully we were unable to process the URI (479/SL)* I can also see the same error message in the console of the Kamailio server. I am hoping that this might mean something to someone enough - to suggest some troubleshooting steps, please. Thanks;