Why hasn't 3CX made this a simple setting for this yet? Looks like this thread is a few years old now. Everyone in my office keeps missing voicemails since they ignore the incessant blinking light which is practically always blinking due to missed calls. This is an office. No one cares about missed calls. We care about voice messages. Everyone's phones ring when there's an inbound call, so when one person answers the call, everyone else gets a missed call registry. This is so stupid. My IT guy is telling me he can write a custom script to fix this issue. Why do I need an IT guy to write a script for something that shouldn't even exist in the first place, and at a minimum be an easily programmable setting??
This thread is only a year old. The issue has been fixed by 3CX in SP2 or SP3 of V15.5, I don't remember which one specifically. Some screenshots to help you out (first make sure you are on the latest 15.5 SP4 version of 3CX with all other updates installed and all phones on the latest 3CX supported firmware version):
First, go to the "Phone Provisioning" tab of the extension (this will have to be done individually for each extension):
Scroll down to "Options", and then find the drop-down menu labeled "Choose how to configure Power LED notifications":
Here you can choose how the notification LED blinks (for missed calls only, voicemail only, or both). This is applicable for Yealink phones but is most likely also applicable for Htek and Snom phones as all three brands (Yealink, Htek, Snom) are highly supported by 3CX.
For your other issue where everyone gets missed call notifications in a ring group even if the call has been answered, please see this thread:
https://www.3cx.com/community/threads/missed-call-alert-for-ring-group.52392/
In short, this issue seems to have been fixed post-SP1. If you have updated to the latest SP4 version and your ring group is set to "Ring All" (and not "Prioritized Hunt") and this issue is still occurring, please post your issue in a new thread and someone should be able to help. If you have purchased a license key from 3CX and you have active support, you can also reach out to 3CX directly by going to customer.3cx.com, logging in with your account ID and password, and going to the "Support" section and opening a new support ticket.