You will have to do it using BAT. Build out the CSV files and use the update phones option. I would export out your existing phones modify the alerting name/caller ID and then re-import it back in. Make sure you check the overwrite settings check box.
Go to Bulk/Import-Export/Export/ select Phones the export the file. Make the change on csv and the go to Bulk/Add New (import/export-Import Configuration). Then go to Bulk/Import-Export/Import and select your file.