Have several customers with the same complaint.
When parking a call with call park: parks the call but does not change the color of the lights on the phones to red. The BLF key stays green, so there is no indication that a call is placed there.
This is on Grandstream GRP2616/2614 phones. The problem is not consistent. Some phones will work, while others do not. I have upgraded firmware versions for the grandstream phones.
I tried versions 220.127.116.11 - 18.104.22.168 - 22.214.171.124
None seem to fix the issue.
The only way I fixed the issue on one phone I had access to was delete the phone from vitalpbx and put it back in and factory reset the phone and paste the URL in the phone once again. After that, the parking lots began working again.
I was hoping someone would have some experience or ideas with this problem, as it is not possible for me to delete and reprovision phones for some of my remote customers that are far away.