The phones are made by Polycom. Polycom has been a leading manufacturer of business phones since 1990 and in 2018, it was acquired by Plantronics and the combined company was renamed to Poly. Because Polycom phones can be used with many different types of phone systems, you won't be able to find much info on how to use them on the Polycom website - because their use differs depending on the system to which they are connected.
The Dialpad phone system supports multiple different phones and can be used in a variety of deployment scenarios; therefore, any information you find on Dialpad's website might not apply to our environment.
DeSales Media created three video tutorials which provide instructions on using the majority of feature on the phones: