IMO, the ideal solutions would be either of the following:
1. Have the user's area code prepended to a 7-digit dial string (current behavior)
2. Allow the user to choose which area code is prepended (IIRC, Voicepulse offers this)

Option 2 should be enabled through vPanel, not solely via submission of a ticket. (Perhaps support could make the change to a provisioning file--only way to know is to ask.)

Obviously, the first option is by far the easiest to implement, but some people may appreciate being able to set the option.