Park Calls are Failing on 8851 SIP Phones

[alecs4]

We're running CUCM 10.5 and the Park feature is not working on 8851 phones. Calls are reverting as soon as I hit "Park". Our 8841 phones work fine with this feature and both types have the same device configurations.

What was done so far:

1. Firmware upgraded to the latest sip88xx.12-1-1SR1-4

2. removed BEKEM 

3. Line Mode does not make a difference (Enhanced and Session)

4. Confirmed Park Numbers are available, other type of phones worked fine with this feature

5. Service Parameters (SIP Park Timers, etc) were  checked

Does anyone experiencing this same issue on 8851 phones?

[Mohammed al Baqari]

I am sure you checked it but do you have the CSS of 8851 able to access
park DNs pt

[alecs4]

Yes, the Park PT is within the CSS.