Map Codes are better than phone numbers because not all places have phone numbers ... like that little scenic water fall you want to visit, or a particular entrance (among many) to a national park. Or a scenic place has a phone number, but it's actually the local chamber of commerce office located miles away.
Google Maps - one time it led me to a closed Uniqlo when I was looking for one in Takayama. Phone number of the current location from the internet didn't work with the in-car GPS - as the lookup database is obsolete the day it leaves the factory.
The best I have found since, is Japanese GPS app. I use Mapfan. Has English voice prompt, but otherwise Japanese interface. It accepts phone and map code input, and has accurate up-to-date map data telephone lookup.