Yes, both the P4K and T4K Yealink models should work properly with Express Talk. Some of Yealink's other phones also work (simply because the driver and functions happen to be similar, meaning it's mostly just coincidental when it does work). Note however that even if you take the risk and get another one of Yealink's phones to work, there is a high chance that some feature(s) won't work properly (e.g. caller ID).
Note there are several other wireless IP/VoIP phones out there that work independently of your computer / the software you're using. These phones connect to a nearby WiFi connection and can be placed anywhere within range and not have to be connected to a PC, Ethernet cable, or any other linking device to work. These phones are sometimes quite expensive however and can rack up $200 in costs depending on the manufacturer.