Phones provisioned through VentureTel's provisioning service are managed through the VentureTel portal (https://control.venturetel.co). To change any BLF keys, login to the VentureTel portal and in SmartPBX, go to 'Devices'.
Then select the wrench under edit of the device you wish to update, then select advanced, and "Feature Keys"
Update the feature keys with 'Presence, Park or Speed Dial' options, then save your settings.
Once the settings are saved, either reboot the phone manually or edit the device again and select 'Miscellaneous' from the advanced menu and select "Send a Restart Request" which should reboot your phone and reprovision the phone with the updated settings.