Understood. The only think I can think of them is that you need to look at the dn that is configured in CME for the 6921. The 6921 and 6941 only support one call per button. It is recommended to configure a 6921/6941 dn as a dual-line dn and place the huntstop channel under the dn. The second channel on the dn can only be used for call transfer or conference.
I had this issue in the past, some of the 6900 IP phones come with signed phone loads. the CME version and limitation on the line button are correct as well. Ensure that you use a signed phone load (for TFTP) on CME beacuse once the phones upgrade to a signed load, it cannot use unsigned images. However, i beleive you can downgrade to a lower signed version. Check the load version and see the release notes.
I had the same issue yesterday while working on 6921 and CME 8.6 running on Cisco ISR G2 2951. Whenever i was trying to make a confrence or was trying to tranfer a call in "Full Consult" mode, it was displaying
"Feature has been disabled on the phone".
Solution that worked for me:
Under ephone configuration run the command "type 6921" and restart the ephone. "Type 6921" command will automatically allow the max-phone calls per button to 2.
If you still face any issue, you can try updating the cnf files under telephone-service and restrating the phone again.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...