Thank you for the update,
I was able to load different firmware on the Phone other than MPP load. While loading the MPP load, it's getting failed. is there anything special to be taken care while loading the MPP load.
The phone you are trying to upgrade is a phone running enterprise firmware (the phone SKU on the back will be CP-7841-K9=. Phones for 3rd party call control and capable of running that firmware are:
CP-78xx-3PCC-K9= (replace the xx for the model you have) or CP-88xx-3PCC-K9=.
If the phone is running enterprise firmware it is locked and can't switch to 3PCC firmware. Factory reset does not remove that "lock" so it remains an "enterprise" phone.
If your question is if you can go from enterprise to 3PCC or viceversa, the answer is no, you cannot.
Phones are hardcoded to either enterprise or 3PCC.
I just want to go from Enterprise to 3PCC. I found the IP Phone 7821 with Multiplatform Firmware. Do you have any updates of this process? Is it possible? I will run the process to upgrading the phone, please advice.