Altigen AltiWare OE/ACC Version 5.0A Administration Manual page 95

Software License Activation and Registration
12. Setup is ready to install the program. Click Install to begin installation.
13. Setup Window will prompt for the Country, System Home Area
Code and Extension Length. When finished, click OK.
Note: Once the Extension Length is set and you click OK, you
cannot change the extension length after this setup unless you
re-configure the entire system or delete all the extensions
already configured.
AltiWare OE System Installation & Administration Manual 3-15