V84.0.140, downgrade no longer possible?

[emaktech]

(01-09-2021 03:39 AM)complex1 Wrote:  @emaktech

Question:
Where are Release Notes for?
Didn't you read those before any firmware upgrade?
It clearly states that you are not allowed to downgrade the phone from current firmware to the previous one, because of "Optimized the upgrade mechanism".
So, is this Yealinks' fault? I personally don't think so. There is no one to force you to upgrade.

If you must know, one of our technicians while onsite onboarding a customer encountered a phone that was carrier locked (e.g. factory reset was password locked). So our tech attempted to do a tftp recovery which used to remove the reset lock. In doing this, they followed our usual procedure which was to use our internal recovery files and simply downloading firmware from Yealink's websites. When that didn't work, we though we would try to downgrade to an older firmware figuring that tftp unlock method didn't work on later firmwares which is when we found out it was now impossible to downgrade the phone. Ergo this phone is now a paperwight and was thrown away.

Do I care about this particular event? Really no, we simply sold the user another phone.

What matters to me is that this makes me very fearful as to whether Yealink has been forced into putting back doors or otherwise into their software for shall we say "regulatory compliance" reasons.

There is no logical explanation as to why a manufacturer would make it impossible to downgrade a firmware. That's a very big step to take and there has to be a very strong reason to do it. Something is very fishy about this change, and if I'm thinking this now, there will probably be more people questioning this over time. We sell 95% Yealink products as it stands, so this could become a huge risk to our business which is why going forward we will need to validate other vendor products and consider moving to them as our primary endpoints.