FRITZ!Box 7581 Service - Knowledge Base
Maximum number of entries in the FRITZ!Box's telephone books
You can create up to 300 entries in each of your local FRITZ!Box telephone books. Telephone books from email accounts (online telephone books) may have up to 1000 entries. If you have several hundred entries, though, it will take longer to open the user interface and slow navigation down noticeably.
Note:The FRITZ!Box does not limit the number of telephone books. Experience has shown that you can use at least 20 telephone books.