QuoteRepresentatives will begin meeting next month to evaluate their technologies, determining, for instance, whether cropping an image would change its signature and hinder comparisons. Also to be discussed are ways to ensure that customers' privacy is protected. Authorities still would need subpoenas to get identifying information on violators. The companies involved said they are talking with other service providers about joining. But companies that do not participate still are required by law to report any suspected child-porn images, and many already have their own techniques for monitoring and identifying them.