I'm having an issue where an agent is not receiving calls using the 3cx softphone. I have provisioned the phone using the provisioning file, logged the agent in to the queues and they don't receive any calls. Running a provisioning file for a different agent on the same computer (same windows login) works fine. I've compared the settings and they all look the same to me. There's an error in the event log on the 3cx server: 02/01/2018 1:12:12 PM - NAT/ALG check:L:13082.1[Extn:2004] REQUEST 'INVITE' - some of SIP/SDP headers may contain inconsistent information or modified by intermediate hop SIP contact header is not equal to the SIP packet source(IPort): Contact address:172.20.74.31:61259 Received from :172.20.74.31:61326 Does anyone have any suggestions?