Thank you Ronak.
I did everything and also checked the URL you provided.
Let everybody know that 3Com 3102A/B (there are two versions) will not work with any CUCM regadless of its version.
The problem is the phones are looking for NCP no matter what. There is a possibility phones to be reflashed with an illegal firmware in order to become true SIP phones but that's not part of the discussion here. I didn't do such thing, just read on Internet, so please don't ask me.