Hello, I have a 3cx server all setup in my office with a voip provider, and everything is working great. I tried to test out the external extension with a Linksys SPA921. I have configured my office firewall that sit in front of the 3cx server exactly as instructed, and have a static public ip and port mapping completed as well as instructed. I am not using a stun server because I believe I read in many posts that if you have a static public ip, you should turn stun off. So I take the external extension home and set it up on the sip manger with my public ip. My router at home is a simple dlink router that has not firewall, nothing else using the viop/sip ports that are required for 3cx to function. At home I do not have a static public ip, so ive tried configuring the phone with and without stun server. Both ways I am able to call out and receive, however I have not outbound audio. Anything I say into my spa921, cannot be heard on the other end. I can hear them just fine though. The router also has a simple “sip” check box within the setup, not sure what its for, but it is checked. I have also tried unchecking it but got same result. Any help would really be appreciated. Thanks.