Hi All I have a Grand Stream HT812. Im quite desperate to try and get it working in 3cx. I realize its not officially supported but a lot of google sees suggestions (But no answers) that it is possible to manually configure this. How do i go about doing so? Just making receiving calls would be great. So far ive tried: 1.)Add an Extension in 3CX. 2.) Configure the HT812 to use the 3CX ip as sip server and provided username and password as given for authentication with phones in the Extensions details. The HT812 just sits at Not registered. Im new to 3CX so would appreciate any suggestions. Thanks in advance.