The problem is in this bug report (Vote for it plz): https://issues.asterisk.org/jira/browse/ASTERISK-27759
The problem is that as BLF’s change their BLF “version” counter increases on both the server and the phone. Some phones and firmwares correctly impliment the RFC Yealink was referring to and reject version counters below their current counter.
Yealink’s new firmware follows that standard and so if the version is at BLF notify #123 it will reject any numbers below #123.
When asterisk restarts it sets that counter to 0 and does not inform the phone. So the next BLF update sends a notify #1 and the phone rejects it because it is below #123.
So yeah this could span across many different brands but only affects the ones that use BLF keys heavily and that properly implement that RFC standard. As I see it the only options are to:
- downgrade yealinks to the 81.0.X firmware that are not reliant on this
- Do not restart asterisk