How to add or change the dialing prefix on the DM300C, DM400C and more

Print this support article
Products affected: DM300C™, DM400C™, and DM475™
Use the following steps to add a prefix number before dialing an outside line:
  1. Press Menu
  2. Press Page Down
  3. Select Data Center Options
  4. Select Phone Settings
  5. Select Dialing Prefix
  6. Enter the prefix number wanted (such as a "9") and select Accept.  The Phone Settings menu returns.
  7. Press the Home key to exit the menu

UPDATED: 14 August 2021