Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: Does this adapter works with Panasonic KX-TG4773B cordless phones?
Document: The output voltage from my wall is around 227V~230V and these chargers work flawlessly. At this time, there is zero humming from either adapter and they are working with my Panasonic KX-TG7642M.Panasonic KX-TG7642M DECT 6.0 Link-to-Cell via Bluetooth Cordless Phone with Answering System - 2 Handsets - Metallic Gray
I Bought 5 Adapters for my Panasonic KX-TG7645M DECT 6.0 Phones.Before 2 months of use, 2 of them have failed.Both of them have failed when plugged on the Base (the second failed after two weeks of use).Maybe the Base require more amps, but original Panasonic adapter for the Base was 500mA too.These adapters have same volts (5.5v) and amps (500mA) than original Panasonic adapters.They are designed for Panasonic Phones!!
Perfect if you use the Panasonic KX in EuropeWorks fine for swap the original power adapter for european power adapters.
220V AC Adapter for Panasonic 5.5V Phones was a very good one which I would recommend for anyone to buy if you need an adapter that can give you an input of 220V and an output of 5.5V.
This adapter is excellent and works great in a 220volt environment. It is not suitable for 110 volt because the plug is made for 220 volt. I gifted 2 of these adapters and a Panasonic phone to someone in 220 volt environment, and it worked without trouble.
Works excellent for my phones in India. But i think it was expensive. Have used for a month so far lets see how long do they last.
I bought a Panasonic cordless phone set and sent it to India and the adapters are working fine for over 3 months now.
It's cheap fits the panasonic phones and it's working.It was easy for purchasing  and it's working very good with panasonic phones I have bought through  Amazon.
Moved from USA to South America and my Panasonic phones work great using these adapters, I received them in good manner and timely for our move.
Delivered promptly. Inexpensive. Does exactly what I wanted (i.e. allows me to buy Panasonic phones much cheaper in the US and use them in higher voltage country).
Answer: Yes, I used it with KX-TG4772B, which is the same system with an additional phone set.