I have seen a lot of questions and answers all over SE about using a passive POE device on an 802.3af network. But can you use an 802.3af device on a passive POE network?
In particular, I have this POE injector that outputs 24V @ 0.5A (12 W?), and a Mitel 5320e IP phone that uses 4.3 W. The phone is 802.3af-compliant, which means it is expecting 48V, but is it reasonable to assume that it would still work on 24V? Or could I expect do damage the device by undervolting it?
It sounds like some people have tried this and it worked OK, but were they just lucky?
What about for the general case: if you have a passive POE injector that outputs 48V, would most 802.3af devices still work on it?
From what I understand, the handshake between the 802.3af POE injector and the device only determines if power will be sent; the device has to adjust the voltage to its needs. Once a 802.3af injector determines the device wants POE, it sends 48V, no matter what. This makes it sounds like 802.3af is just to protect non-POE devices. If that is correct, than a passive injector is only dangerous to non-POE devices; it shouldn't be dangerous to POE devices, even if they use a different standard. Is that correct?
More details on what I'm trying to do here