As a matter of fact, there is a SCCP driver that you can use with these phones to make them work like they would with CUCM. Check Github for chan-sccp-b - Interesting new success with Chan-SCCP-B and SCCP-Manager (both from GitHub) - is a good first step.
We’ve had a few people report plenty of success with the software using many different versions of these phones. Installing the software requires up recompiling of Asterisk and leaves the phones in the native software version.