Without proper end-user training any phone system deployment, no matter how well it has been designed, will be doomed to failure. The users need to be given live instructions in front of a phone and need some take-away instructions for future reference when they forget everything they were taught. Some users learn through doing, some through reading and studying. Give users the option to do both.
The user manuals that come with phones are typically very large and confusing to most users. To help your users along it is a good idea to develop some small tri-fold or single page instructions for each type of phone being deployed. Make sure to cover even the basics of dialing numbers and adjusting the phone volume. The following is an example of a tri-fold that was created for the Polycom 650. The first page contains the outside document description, a section for the end user to add custom notes, and instructions for dialing.
As seen in the following screenshot...