This article relates to Cisco TelePresence Management Suite.
Q. In TMS, what is the difference between "Phone Books Update Frequency" and "Update Frequency for an External Source"?
A. Update Frequency on a Connected External Source determines how often that data source is synchronized to the phone book stored on TMS.
Under Administrative Tools > Configuration > General , the Phone Books Update Frequency setting determines how often phone books stored on TMS are pushed to systems that use the Global Directory. For systems that do not use Global Directory, this setting has no effect.