Auto-add "home" area code when dialing 7 digits

[daniels220]

I recently switched VoIP providers, and the old one would automatically add my home area code server-side if I dialed 7 digits, but with the new one, the only way I can have 7-digit dialing is to make it part of the "dial plan" string I configure in my ATA (an entry like <:1734>[2-9]xxxxxx), and Telephone doesn't have an equivalent. Full dial-plan support would be cool and would be one option, but some of the capabilities there are redundant since pressing Return acts as the "send call" signal so there is no need to disambiguate, so the least-effort solution would be a "home area code" option that is automatically prepended when exactly 7 digits are dialed.