Question : How do I configure a Polycom IP 330 or 321 to replace a softphone

I am currently using softphones (3CX, X-Lite) with my virtual PBX provider and want to replace some of them with Polycom IP phones. I have tried configuring the phones (IP 321, IP 330) using their built-in http configuration but to no avail. The phones have the latest firmware. I assume that since the softphones use SIP and the Polycoms are SIP phones that this should work. I have found a few example setups online but none of them work.

Answer : How do I configure a Polycom IP 330 or 321 to replace a softphone

Try changing the Transport to TCPpreferred or TCPOnly if available on your firmware. Also, I would try then deleting the Address field from the Line1 Configuration