There are lots of cd's without ISRC codes. There is no obligation to use them, they are just a convenient way to identify a piece of recorded music.AFAIK the consumer shouldn't be bothered with ISRC codes. What is your intended purpose ?
If there is a scenario in which one must know the ISRC of a track for some reason, I’d assume a database of ISRCs exists somewhere—one that is not reliant on their optional storage in CD subcodes—otherwise, that is a very draconian requirement.
The question is, where?
This may seem like a dumb question, but does anyone know of a ISRC-based DB publicly available on the web?
4.1.5 Registration in Repertoire Databases Whilst there is no obligation in ISO3901: 2001 to keep records (beyond those needed to ensure uniqueness), nor to register the assignment with the National Agency or any other body, there is little value in the ISRC system without such records being kept and comprehensive databases being maintained. It is therefore strongly recommended that Registrants keep good records and ensure that the details of the recording (the metadata) and the ISRC allocated, are included in relevant repertoire databases. The International ISRC Agency can provide advice on the appropriate database in particular circumstances.