Hi Dears, We are trying for test version of 3CX Software with Cisco SPA502G IP phones in our company. In the probationary period could have picked a problem with using 3CX SIP Proxy Manager. In that; We installed the proxy manager to remote host, configured and tested along with a Cicso SPA502G IP Phone. We have successfully completed the configuration from the website by taking samples scenario. (http://www.3cx.com/blog/releases/sip-proxy-manager/). We configured router and firewall settings as correctly, First added extension status is green and working well. Ringing, 2 ways sound communication is OK. There is no problem. After that we have tried to add 2nd and 3rd Ipphone (Cisco SPA502G) and configured provisioning settings for extension as remotely (like first one), according to instruction of 3CX web site samples again as well. (http://www.3cx.com/blog/docs/provisioning-a-remote-extension/) BUT; in the second and third IP Phones, not receiving any respons from the 3CX Phone System Management software. The provisioning and registration not working. Also we have tried to set as manually provisioning script and settings like samples from website of 3CX, but still not provisioning. (http://www.3cx.com/blog/docs/provisioning-a-remote-extension/) Still extension 127 is working with remote extension via sip proxy tunnel. But 124 and 201 is not. If any idea of anyone, please share with me the ideas, solutions.... Thank you. Sezgin.